Merge fa02b20067 into 88e5be6e4b

fix spelling and whitespace in cheatsheets

backend/solidity.sol

@@ -0,0 +1,220 @@
+/* *******************************************************************************************
+ * Defining Licensing of the smart contract =>
+ ******************************************************************************************** */
+
+// SPDX-License-Identifier: MIT
+// List of allowed SPDX licenses to use => https://spdx.org/licenses/
+
+/* *******************************************************************************************
+* Defining solidity compiler(solc) version for compiling the smart contract => 
+    - Some possible ways to use:
+        - pragma solidity 0.8.0; ==> compiler version set exactly on 0.8.0 version
+        - pragma solidity ^0.8.0; ==> compiler version set above 0.8.0 version and lower than 0.9.0 version
+        - pragma solidity >= 0.7.0 < 0.9.0; ==> compiler version set equal or above 0.7.0 version and lower than 0.9.0 version
+******************************************************************************************** */
+
+pragma solidity ^0.8.0;
+
+/* *******************************************************************************************
+* Creating the smart contract => contract ContractName {}
+
+ -   Note: Contracts are like classes in other programming languages.
+ -   Note: Naming convention is like this for declaring contract: MyContract
+
+ ******************************************************************************************** */
+contract HelloWorld {
+    /* *******************************************************************************************
+
+* Data types:
+    * 1) Value types:
+        - Value stored in smart contract storage slot
+            - bool
+            - int
+            - uint
+            - address
+            - bytes1 ... bytes32
+            - enum
+    
+    * 2) Reference types:
+        - A reference to a stored value in smart contract storage slot will be set
+            - array
+            - string
+            - mapping
+            - struct
+            - bytes
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+
+* Variable types:
+   * 1) State variables => Variables which
+        - Get permanently stored on blockchain(smart contract storage)
+        - Use most gas usage in smart contracts
+        - Accessible on whole smart contract
+
+   * 2) Local variables => Variables which
+        - Not stored on blockchain
+        - Use less gas in smart contracts
+        - Are living and working just in function body
+
+   * 3) Global variables => Variables which
+        - Provide information about the blockchain
+        - Can be used both as state variables and local variables
+        - Mainly used to determine contract owner and checking time
+******************************************************************************************** */
+    /* *******************************************************************************************
+
+* Visibility:
+    * 1) Variables:
+            - public
+            - private
+            - internal
+
+            * Ex: uint public number;
+            
+            - Note: visibility is just for state variables and not applicable on local variables
+            - Note: default visibility of a state variable is(if we don't declare visibility scope) --> internal
+            - Note: if declare a variable to have 'public' scope, automatically a 'getter function' will be created for that variable
+    
+    * 2) Functions:
+            - public
+            - private
+            - internal
+            - external
+
+        * Ex: function setNumber() public {}
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+
+* Function types:
+   * 1) Non-Payable => Functions which
+        - Write on the blockchain
+        - Are our default functions type
+        - Are not able to accept deposits on the smart contract
+
+        * Ex: function setNumber() public {}
+
+   * 2) View => Functions which
+        - Are able to show us data
+        - Read from blockchain
+
+        * Ex: function setNumber() public view {}
+
+   * 3) Pure => Functions which
+        - Neither read nor write on blockchain
+        - Just do a specific work for us (ex: making sum of 2 numbers and returning back the value)
+
+        * Ex: function setNumber() public pure {}
+
+   * 3) Payable => Functions which
+        - Are able to accept Ether deposits on the smart contract
+
+        * Ex: function setNumber() public payable {}
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+* Constructor => A function which
+    - Is optional
+    - Does not have a name
+    - Does not have visibility scope
+    - Executed during contract deployment
+    - Can take parameters while deploying
+    - Initializes smart contract state variables
+    - Will be at most 1 within each smart contract
+    - Can have payable attribute associatede with it
+
+        * Ex: constructor(uint _number) { number = _number; }
+******************************************************************************************** */
+    /* *******************************************************************************************
+ * Data Locations =>
+    * Each variable declared and used in a contract has a data location:
+        - Storage:
+            - global memory available to all functions within a contract.   
+            - oermanent storage that Ethereum stores on every node.
+        - Memory:
+            - local memroy available to every function within a contract.
+            - short living in functions.
+        - Calldata:
+            - where all incoming function execution data is stored(including function arguments)
+            - non-modifiable memory location(note: similar to memrory location, except it is not modifiable)
+        - Stack
+            - a stack which is maintained by EVM(Etheereum Virtual Machine) for loading variables and 
+                intermediate values for working with Ethereum instruction set(the working set memory for the EVM).
+            - max limit is 1024 levels, and exceeding this limit(by storing anything more than that), raises an exception.
+
+    - Note: data location of variable, is dependent on:
+        - Location of the variable declaration
+        - Data type of the variable
+    - Note: We face them mostly, when are working with reference type variables.
+
+ ******************************************************************************************** */
+    /* *******************************************************************************************
+* Events => 
+    - Used for logging(like other languages)
+    - Used to notify applications about changes in contracts
+    - can be used to "call" JavaScript callbacks in the user interface of a dapp
+    - Primarily for informing the calling application about the current state of the contract
+    - Declared with 'event' keyword
+    - Firing them with 'emit' keyword
+
+    - Note: Events can be declared anonymous.
+    - Note: Events can have 'indexed' keyword in variable declaration(to make easier filtering of some specific data)
+
+        * Ex: event EventName(address sender,uint number)
+        *     emit EventName(address(0), 10)
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+* Error handling => 
+   * 1) Require
+        - Check a condition, 
+            if true => go to next line codes,
+            if false => show a string message and revert to privious state
+        - Refund remaining gas to the caller
+        
+        - Note: Use require conditions, all at beginning the function.
+
+            * Ex: require(number >= 10, "number must be greater than 10");
+
+   * 1) Revert
+        - Similar to require, but can have more complex conditions
+        - Refund remaining gas to the caller
+
+            * Ex: if(number <= 10) { revert("number must be greater than 10"); }
+
+   * 1) Assert
+        - Mainly used in writing contract tests
+        - Don't refund remaining gas to the caller
+
+
+        * Ex: uint number = 123;
+        *   assert(number == 10);
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+* Enum =>
+    - A user defined data type
+    
+      * Ex: enum OrderStatus { pending, accepted, completed, rejected};
+      *      OrderStatus order = OrderStatus.accepted;
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+* Mapping => 
+    * Declaration: `mapping(_KeyType => _ValueType) mappingName`
+    - Mappings are like **Dictionary** or **hash table** which are virtually initialized 
+        such that every possible key exists and is mapped to a specific value.
+    - Note: **key** can be any type which EVM internally knows about it(exceptions are: a dynamically sized array, a contract, an enum, or a struct.
+    - Note: **value** can actually be any type, including mappings.
+
+******************************************************************************************** */
+    /* *******************************************************************************************
+
+* Struct
+    * Somehow we can pack some data types(and ofcourse data values) of an specific entity with structs:
+
+      * Ex: struct UserInfo { string fName; string lName; uint8 age; address wallet;}
+      *  UserInfo user;
+******************************************************************************************** */
+}

databases/mysql.sh

@@ -16,3 +16,69 @@ GRANT ALL PRIVILEGES ON prospectwith.* TO 'power'@'localhost' WITH GRANT OPTION;
 CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'password'; # Create user
 
 mysql -u root -pmypassword -e "MY SQL QUERY" &>> query.log & disown # Run SQL query in the background
+
+# *****************************************************************************
+# Database and Table Operations
+# *****************************************************************************
+
+CREATE DATABASE database_name; # Create a new database
+DROP DATABASE database_name; # Delete a database
+CREATE TABLE table_name (column1 datatype, column2 datatype, ...); # Create a new table
+DROP TABLE table_name; # Delete a table
+SHOW TABLES; # Display all tables in the current database
+DESCRIBE table_name; # Show the structure of a table
+
+# *****************************************************************************
+# Data Manipulation
+# *****************************************************************************
+
+INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...); # Insert data into a table
+UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition; # Update existing data in a table
+DELETE FROM table_name WHERE condition; # Delete data from a table
+SELECT column1, column2, ... FROM table_name WHERE condition; # Select data from a table
+
+# *****************************************************************************
+# Backup and Restore
+# *****************************************************************************
+
+mysqldump -u username -p database_name table1 table2 > file.sql # Backup specific tables
+mysql -u username -p database_name < file.sql # Restore specific tables
+
+# *****************************************************************************
+# User Management and Security
+# *****************************************************************************
+
+REVOKE privilege_type ON database_name.table_name FROM 'username'@'hostname'; # Revoke privileges from a user
+DROP USER 'username'@'hostname'; # Delete a user
+ALTER USER 'username'@'hostname' IDENTIFIED BY 'newpassword'; # Reset a user's password
+
+# *****************************************************************************
+# Performance and Maintenance
+# *****************************************************************************
+
+OPTIMIZE TABLE table_name; # Optimize a table
+ANALYZE TABLE table_name; # Analyze a table for key distribution and storage optimization
+CHECK TABLE table_name; # Check a table for errors
+REPAIR TABLE table_name; # Repair a corrupted table
+
+# *****************************************************************************
+# Advanced Queries
+# *****************************************************************************
+
+SELECT ... FROM table1 JOIN table2 ON table1.column = table2.column; # Perform a join operation between two tables
+SELECT ... FROM (SELECT ... FROM table_name) AS subquery; # Use a subquery within another query
+SELECT column, COUNT(*) FROM table_name GROUP BY column; # Group results and use aggregate functions
+
+# *****************************************************************************
+# System Information
+# *****************************************************************************
+
+SELECT VERSION(); # Show the current version of MySQL
+SELECT User, Host FROM mysql.user; # List all current MySQL users
+
+# *****************************************************************************
+# Miscellaneous
+# *****************************************************************************
+
+SET GLOBAL general_log = 'ON'; # Enable query logging
+SHOW FULL PROCESSLIST; # Show the last queries executed in MySQL

languages/C#.txt

@@ -3,7 +3,7 @@ CHEATSHEET C#
 1. Data Types
 
     Primitive   Size            Example
-    
+
     String      2 bytes/char    s = "reference";
     bool                        b = true;
     char        2 bytes         ch = 'a';
@@ -16,20 +16,20 @@ CHEATSHEET C#
     decimal     16 bytes        val = 70.0M;
 
 2. Arrays
-    
+
     2.1 Declaration
 
     //Initiliazed using a list defined with curly braces
     int[] nameArray = {100, 101, 102};
-    
+
     //Define an empty array
     int[] nameArray = new int[3]; // 3 rows and 2 columns
-    
+
     //To access a specific item in the array
     int[] nameArray = new int[10];
     int firstNumber = nameArray[0];
     nameArray[1] = 20;
-    
+
     //Multidimensional arrays
     int [,] matrix = new int [2,2]
     matrix[0,0] = 1;
@@ -40,26 +40,26 @@ CHEATSHEET C#
     int[,] predefinedMatrix = new int[2,2] { { 1, 2 }, { 3, 4 } };
 
     2.2 Array Operations
-    
+
     //Sort ascending
     Array.Sort(nameArray);
-    
+
     //Sort begins at element 6 and sorts 20 elements
     Array.Sort(nameArray,6,20);
-    
+
     //Use 1 array as a key & sort 2 arrays
     string[] values = {"Juan", "Victor", "Elena"};
     string[] keys = {"Jimenez", "Martin", "Ortiz"};
     Array.Sort(keys, values);
-    
+
     //Clear elements in array (array, first element, # elements)
     Array.Clear(nameArray, 0, nameArray.Length);
-    
+
     //Copy elements from one array to another
     Array.Copy(scr, target, numOfElements);
 
 3. String Operations
-    
+
     //To concatenate between strings, use the plus operator:
     string firstName = "Erin";
     string lastName = "Roger";
@@ -68,27 +68,27 @@ CHEATSHEET C#
     //To add one string to another, use the += operator:
     string secondLastName = "Green";
     string fullName += secondLastName;
-    
+
     //ToString function
     //It converts an object to its string representation so that it is suitable for display
     Object.ToString();
-    
+
     //String formatting
     //Each additional argument to the function can be referred to in the string using the brackets operator with the index number.
     String.Format(String format, Object arg0);
-     format - A composite format string that includes one or more format items 
+     format - A composite format string that includes one or more format items
      arg0 - The first or only object to format
 
     //Substring
     //Returns a part of the string, beginning from the index specified as the argument. Substring also accepts a maximum length for the substring
     String.Substring(beginAt);
     String.Substring(beginAt, maximum);
-    
+
     //Replace
     string newStr = oldStr.Replace("old","new");
 
     //IndexOf
-    //Finds the first ocurrence of a string in a larger string
+    //Finds the first occurrence of a string in a larger string
     //Returns -1 if the string is not found
     String.IndexOf(val, start, num)
     val - string to search for
@@ -102,7 +102,7 @@ CHEATSHEET C#
     String.Split(Char[]);
 
     //ToCharArray
-    //Places selected characteres in a string in a char array
+    //Places selected characters in a string in a char array
     String str = "AaBbCcDd";
     //create array of 8 vowels
     var chars = str.ToCharArray();
@@ -132,11 +132,11 @@ CHEATSHEET C#
     DateTime nextYear = DateTime.AddYears(1);
 
 6. TimeSpan
-    
+
     6.1 TimeSpan Constructor
-        
-    TimpeSpan(hour, minute, sec)
-    
+
+    TimeSpan(hour, minute, sec)
+
     TimeSpan timeS = new TimeSpan(10, 14, 50);
     TimeSpan timeS_Hours = TimeSpan.FromDays(3640);
 
@@ -144,8 +144,8 @@ CHEATSHEET C#
 
     Format item syntax: {index[,alignment][:format string]}
     index - Specifies element in list of values to which format is applied
-    aligment - Indicates minimun width (in characters) to display value
-    format string - Contains the code which specififes the format of the displayed value
+    alignment - Indicates minimum width (in characters) to display value
+    format string - Contains the code which specifies the format of the displayed value
 
     7.1 Numeric
 
@@ -168,7 +168,7 @@ CHEATSHEET C#
     csc -define:DEBUG -optimize -out:File2.exe *.cs -> Compiles all the C# files in the current directory with optimizations enabled and defines the DEBUG symbol. The output is File2.exe
     csc -target:library -out:File2.dll -warn:0 -nologo -debug *.cs -> Compiles all the C# files in the current directory producing a debug version of File2.dll. No logo and no warnings are displayed
     csc -target:library -out:Something.xyz *.cs -> Compiles all the C# files in the current directory to Something.xyz (a DLL)
-    
+
     8.1 Compiler Options Listed
 
     Option	                    Purpose
@@ -260,21 +260,21 @@ CHEATSHEET C#
 10. Loop
 
     10.1 While
-    
+
     while (condition) {body}
-    
+
     10.2 Do while
 
     do {body} while condition;
-    
+
     10.3 For
 
     for (initializer; termination condition; iteration;) {
             //statements
     }
-    
+
     10.4 For each
-    
+
     foreach (type identifier in collection)  {
         //statements
     }
@@ -293,7 +293,7 @@ CHEATSHEET C#
     [access modifier] className (parameters) [:initializer]
 
     initializer -base calls constructor in base class.
-                 this calls constuctor within class.
+                 this calls constructor within class.
 
     public class nameClass : Initializer {
         public className(dataType param1 , dataType param2, ...) : base(param1, param2)
@@ -313,8 +313,8 @@ CHEATSHEET C#
     abstract – must be implemented by subclass
 
     Passing parameters:
-        1. By default, parametres are passed by value
-        2. Passing by reference: ref, in and out modifers
+        1. By default, parameters are passed by value
+        2. Passing by reference: ref, in and out modifiers
 
     To pass a parameter by reference with the intent of changing the value, use the ref, or out keyword. To pass by reference with the intent of avoiding copying but not changing the value, use the in modifier
 
@@ -331,9 +331,9 @@ CHEATSHEET C#
 12. Struct
 
     12.1 Defining a structure
-    
+
     [attribute][modifier] struct name [:interfaces] { struct-body }
-    
+
     12.2 Class vs Structure
 
        -> Classes are reference types and structs are value types
@@ -378,7 +378,7 @@ CHEATSHEET C#
     //To declare an event inside a class, first a delegate type for the event must be declared.
 
     public delegate string MyDelegate(string str);
-    
+
     //The event itself is declared by using the event keyword
 
     event MyDelegate MyEvent;

languages/C.txt

@@ -31,11 +31,11 @@ Preprocessor directives:
 
 Create and execute a program
 
-In Linux systems: 
+In Linux systems:
     1. Open up a terminal
     2. Create the program: nano nameProgram.c
     3. Write the program and save it
-    4. gcc -o nameExecutable nameProgram.c 
+    4. gcc -o nameExecutable nameProgram.c
 
 32 Reserved words
 
@@ -106,8 +106,8 @@ Operators
 
   ( )	  grouping parenthesis, function call
   [ ]	  array indexing, also  [ ][ ]  etc.
-  ->   	selector, structure pointer  
-  .	    select structure element     
+  ->   	selector, structure pointer
+  .	    select structure element
   !	    relational not, complement, ! a  yields true or false
   ~    	bitwise not, ones complement, ~ a
   ++  	increment, pre or post to a variable
@@ -153,7 +153,7 @@ Operators
 
 
 Operator precedence
-                
+
 More precedence
 
 LR	( ) [ ] -> . x++ x--
@@ -203,7 +203,7 @@ Function definition
 
 type function_name(int a, float b, const char * ch,...) { function_body }
 
-/* only parameters passed by address can are modified*/ 
+/* only parameters passed by address can are modified*/
 
 /* in the calling function, local copy can be modified*/
 

languages/XML.md

@@ -11,7 +11,7 @@ XML uses a DTD to describe the data.
    So the XML is a **Complement** to HTML.
 * HTML: is used to format and display the same data.
 
-   
+
 XML does not carry any information about how to be displayed. The same XML data can be used in many different presentation scenarios.
 Because of this, with XML, there is a full separation between data and presentation.
 

languages/bash.sh

@@ -46,7 +46,7 @@ CTRL+X then (   # start recording a keyboard macro
 CTRL+X then )   # finish recording keyboard macro
 CTRL+X then E   # recall last recorded keyboard macro
 CTRL+X then CTRL+E   # invoke text editor (specified by $EDITOR) on current command line then execute resultes as shell commands
-CTRL+A then D  # logout from screen but don't kill it, if any command exist, it will continue 
+CTRL+A then D  # logout from screen but don't kill it, if any command exist, it will continue
 
 BACKSPACE  # deletes one character backward
 DELETE     # deletes one character under cursor
@@ -94,7 +94,7 @@ cat <filename>                # displays file raw content (will not be interpret
 cat -n <filename>             # shows number of lines
 nl <file.sh>                  # shows number of lines in file
 cat filename1 > filename2     # Copy filename1 to filename2
-cat filename1 >> filename2    # merge two files texts together 
+cat filename1 >> filename2    # merge two files texts together
 any_command > <filename>      # '>' is used to perform redirections, it will set any_command's stdout to file instead of "real stdout" (generally /dev/stdout)
 more <filename>               # shows the first part of a file (move with space and type q to quit)
 head <filename>               # outputs the first lines of file (default: 10 lines)
@@ -203,14 +203,14 @@ echo $$                      # prints process ID of the current shell
 echo $!                      # prints process ID of the most recently invoked background job
 echo $?                      # displays the exit status of the last command
 read <varname>               # reads a string from the input and assigns it to a variable
-read -p "prompt" <varname>   # same as above but outputs a prompt to ask user for value 
+read -p "prompt" <varname>   # same as above but outputs a prompt to ask user for value
 column -t <filename>         # display info in pretty columns (often used with pipe)
 let <varname> = <equation>   # performs mathematical calculation using operators like +, -, *, /, %
 export VARNAME=value         # defines an environment variable (will be available in subprocesses)
 export -f  <funcname>        # Exports function 'funcname'
 export var1="var1 value"     # Export and assign in the same statement
-export <varname>             # Copy Bash variable 
-declare -x <varname>         # Copy Bash variable 
+export <varname>             # Copy Bash variable
+declare -x <varname>         # Copy Bash variable
 
 array[0]=valA                # how to define an array
 array[1]=valB
@@ -507,9 +507,9 @@ function returntrap {
 trap returntrap RETURN  # is executed each time a shell function or a script executed with the . or source commands finishes executing
 
 ##############################################################################
-# COLORS AND BACKGROUNDS 
+# COLORS AND BACKGROUNDS
 ##############################################################################
-# note: \e or \x1B also work instead of \033 
+# note: \e or \x1B also work instead of \033
 # Reset
 Color_Off='\033[0m' # Text Reset
 
@@ -524,14 +524,14 @@ Cyan='\033[0;36m'   # Cyan
 White='\033[0;97m'  # White
 
 # Additional colors
-LGrey='\033[0;37m'  # Ligth Gray
+LGrey='\033[0;37m'  # Light Gray
 DGrey='\033[0;90m'  # Dark Gray
-LRed='\033[0;91m'   # Ligth Red
-LGreen='\033[0;92m' # Ligth Green
-LYellow='\033[0;93m'# Ligth Yellow
-LBlue='\033[0;94m'  # Ligth Blue
+LRed='\033[0;91m'   # Light Red
+LGreen='\033[0;92m' # Light Green
+LYellow='\033[0;93m'# Light Yellow
+LBlue='\033[0;94m'  # Light Blue
 LPurple='\033[0;95m'# Light Purple
-LCyan='\033[0;96m'  # Ligth Cyan
+LCyan='\033[0;96m'  # Light Cyan
 
 
 # Bold
@@ -566,6 +566,6 @@ On_White='\033[47m' # White
 
 # Example of usage
 echo -e "${Green}This is GREEN text${Color_Off} and normal text"
-echo -e "${Red}${On_White}This is Red test on White background${Color_Off}" 
+echo -e "${Red}${On_White}This is Red test on White background${Color_Off}"
 # option -e is mandatory, it enable interpretation of backslash escapes
 printf "${Red} This is red \n"

languages/golang.md

@@ -397,8 +397,8 @@ d, t := doubleAndTriple(5)
 _, t := doubleAndTriple(3)
 // t = 9
 
-// Functions can defer commands. Defered commands are
-// runned in a stack order after the execution and
+// Functions can defer commands. Deferred commands are
+// ran in a stack order after the execution and
 // returning of a function
 var aux = 0
 
@@ -488,7 +488,7 @@ person3.Age // 0
 
 ## Maps
 
-Maps are data structures that holds values assigneds to a key.
+Maps are data structures that holds values assigned to a key.
 
 ```go
 // Declaring a map
@@ -508,7 +508,7 @@ newYork // "EUA"
 // Delete
 delete(cities, "NY")
 
-// Check if a key is setted
+// Check if a key is set
 value, ok := cities["NY"]
 ok // false
 value // ""
@@ -600,7 +600,7 @@ Go doesn't support `throw`, `try`, `catch` and other common error handling struc
 ```go
 import "errors"
 
-// Function that contain a logic that can cause a possible exception flow 
+// Function that contain a logic that can cause a possible exception flow
 func firstLetter(text string) (string, error) {
     if len(text) < 1 {
         return nil, errors.New("Parameter text is empty")
@@ -632,7 +632,7 @@ func Sum(x, y int) int {
 }
 
 // main_test.go
-import ( 
+import (
     "testing"
     "reflect"
 )
@@ -676,7 +676,7 @@ func main() {
     blocking2: 0
     blocking2: 1
     blocking2: 2
-    done 
+    done
 */
 
 // Go routines are a function (either declared previously or anonymous) called with the keyword go

languages/java.md

@@ -204,7 +204,7 @@ a \|= b; //a is the variable name; b is the variable name; this expression is an
   }
 ```
 **Example:**
-```java  
+```java
   for (int i = 0; i <= n; i++) {
      System.out.println(i);
   }
@@ -254,10 +254,10 @@ for(dataType item : array) {
 
 **Example:**
 ```java
-    int i=1;  
-    do{  
-      System.out.println(i);  
-      i++;  
+    int i=1;
+    do{
+      System.out.println(i);
+      i++;
     }while(i<=10);
 ```
 
@@ -308,7 +308,7 @@ for(dataType item : array) {
   //Declare a variable, object name
   String s;
 
-  //Invoke a contructor to create an object
+  //Invoke a constructor to create an object
   s = new String ("Hello World");
 
   //Invoke an instance method that operates on the object's value
@@ -361,13 +361,13 @@ class MyClass {
         // four methods
         public void setCadence(int newValue) {
             cadence = newValue;
-        }   
+        }
         public void setGear(int newValue) {
             gear = newValue;
-        }   
+        }
         public void applyBrake(int decrement) {
             speed -= decrement;
-        }  
+        }
         public void speedUp(int increment) {
             speed += increment;
         }
@@ -531,13 +531,13 @@ class MyClass extends MySuperClass implements YourInterface {
 
 
 ```java
-    interface print{  
-        void printPaper();  
-    }  
-    public class A4 implements print{  
+    interface print{
+        void printPaper();
+    }
+    public class A4 implements print{
         public void printPaper(){
           System.out.println("A4 Page Printed. ");
-        }  
+        }
     }
 ```
 

languages/php.php

@@ -1,8 +1,8 @@
 <?php
 
 // Exit the file, string inside get's echo'ed
-die("This file is not ment to be ran. ¯\_(ツ)_/¯");
-exit("This file is not ment to be ran. ¯\_(ツ)_/¯");
+die("This file is not meant to be ran. ¯\_(ツ)_/¯");
+exit("This file is not meant to be ran. ¯\_(ツ)_/¯");
 
 /**
  * Printing
@@ -17,7 +17,7 @@ var_dump($arr); // Print anything, with type hints for any value and sizes
 $string = 'Awesome cheatsheets';
 
 str_contains($string, 'cheat'); // Find if the string contains the specified string (PHP >= 8.0)
-str_replace('Awesome', 'Bonjour', $string); // Replace all occurence
+str_replace('Awesome', 'Bonjour', $string); // Replace all occurrence
 strcmp($string, 'Awesome cheatsheets'); // Compare two strings
 strpos($string, 'a', 0); // Get position in the string
 str_split($string, 2); // Split the string
@@ -189,7 +189,7 @@ $argc; // Number of arguments passed into terminal
  $myObject?->getName()?->startWith('A');
 
 /**
- * Class 
+ * Class
  * http://php.net/manual/en/language.oop5.basic.php
  */
 class NormalClass extends AbstractClassName implements InterfaceName
@@ -200,7 +200,7 @@ class NormalClass extends AbstractClassName implements InterfaceName
     // --> PROPERTY TYPES <--
 
     /**
-     * Public property, everyone can access this property. 
+     * Public property, everyone can access this property.
      * @var Type
      */
     public $property;
@@ -251,7 +251,7 @@ class NormalClass extends AbstractClassName implements InterfaceName
     protected function protectedFunction(Type $var = null): Type
     {
     }
-    
+
     /**
      * Static function, doesn't need an instance to be executed.
      * @param Type
@@ -541,7 +541,7 @@ u   Pattern is treated as UTF-8
 \w  Any "word" character (a-z 0-9 _)
 \W  Any non "word" character
 \s  Whitespace (space, tab CRLF)
-\S  Any non whitepsace character
+\S  Any non whitespace character
 \d  Digits (0-9)
 \D  Any non digit character
 .   (Period) - Any character except newline

languages/python.md

@@ -44,7 +44,7 @@
 - As of python3.8 there are 35 keywords
 
 | Keyword | Description  | Category |
-|---------- | ---------- | --------- | 
+|---------- | ---------- | --------- |
 | True      | Boolean value for not False or 1 | Value Keyword|
 | False     | Boolean Value for not True or 0 | Value Keyword |
 | None      | No Value | Value keyword |
@@ -58,7 +58,7 @@
 | else | this block will be executed if condition is false | conditional |
 | for | used for looping | iteration |
 | while | used for looping | iteration |
-| break | get out of loop | iteration | 
+| break | get out of loop | iteration |
 | continue | skip for specific condition | iteration |
 | def | make user defined function | structure |
 | class | make user defined classes | structure |
@@ -71,8 +71,8 @@
 | import | import libraries/modules/packages | import |
 | from | import specific function/classes from modules/packages | import |
 | try | this block will be tried to get executed | exception handling |
-| except | is any exception/error has occured it'll be executed | exception handling |
-| finally | It'll be executed no matter exception occurs or not | exception handling | 
+| except | is any exception/error has occurred it'll be executed | exception handling |
+| finally | It'll be executed no matter exception occurs or not | exception handling |
 | raise | throws any specific error/exception | exception handling |
 | assert | throws an AssertionError if condition is false | exception handling |
 | async | used to define asynchronous functions/co-routines | asynchronous programming |
@@ -135,7 +135,7 @@
 - Lists are created using square brackets:
 
 ```python
-thislist = ["apple", "banana", "cherry"] 
+thislist = ["apple", "banana", "cherry"]
 ```
 
 - List items are ordered, changeable, and allow duplicate values.
@@ -157,14 +157,14 @@ thislist = list(("apple", "banana", "cherry"))  # note the double round-brackets
 - pop() function removes the last value in the given list by default.
 
   ```python
-  thislist = ["apple", "banana", "cherry"] 
-  
+  thislist = ["apple", "banana", "cherry"]
+
   print(thislist.pop())  # cherry
-  print(thislist.pop(0))  #apple 
-  
+  print(thislist.pop(0))  #apple
+
   ```
 
-  
+
 
 ### Tuple
 
@@ -291,14 +291,14 @@ thisdict = {
     "model": "Mustang",
     "year": 1964
   }
-  
+
   x = car.pop("model")
-  
+
   print(x)# Mustang
   print(car)#{'brand': 'Ford', 'year': 1964}
   ```
 
-  
+
 
 ### Conditional branching
 
@@ -378,5 +378,5 @@ function_name()
 ```
 
 * We need not to specify the return type of the function.
-* Functions by default return `None` 
+* Functions by default return `None`
 * We can return any datatype.

tools/vim.txt

@@ -1,6 +1,6 @@
 ##############################################################################
 # VIM CHEATSHEET
-# WEBSITE: http://www.vim.org/  
+# WEBSITE: http://www.vim.org/
 # DOCUMENTATION: https://vim.sourceforge.io/docs.php
 ##############################################################################
 
@@ -20,13 +20,15 @@ e                   jump to end of words (punctuation considered words)
 E                   jump to end of words (no punctuation)
 b                   jump backward by words (punctuation considered words)
 B                   jump backward by words (no punctuation)
-ge                  jump backward to end of words
+ge                  jump backward to end of a word
+gE                  jump backwards to the end of a word (words can contain punctuation)
 0                   (zero) start of line
 ^                   first non-blank character of line
-$                   end of line
--                   move line upwards, on the first non blank character
-+                   move line downwards, on the first non blank character
-<enter>             move line downwards, on the first non blank character
+$                   jump to the end of the line
+g_                  jump to the last non-blank character of the line
+-                   move line upwards, on the first non-blank character
++                   move line downwards, on the first non-blank character
+<enter>             move line downwards, on the first non-blank character
 gg                  go to first line
 G                   go to last line
 ngg                 go to line n
@@ -38,10 +40,6 @@ nG                  go To line n
 }                   move the cursor a paragraph forwards
 ]]                  move the cursor a section forwards or to the next {
 [[                  move the cursor a section backwards or the previous {
-CTRL-f              move the cursor forward by a screen of text
-CTRL-b              move the cursor backward by a screen of text
-CTRL-u              move the cursor up by half a screen
-CTRL-d              move the cursor down by half a screen
 H                   move the cursor to the top of the screen.
 M                   move the cursor to the middle of the screen.
 L                   move the cursor to the bottom of the screen.
@@ -49,6 +47,16 @@ fx                  search line forward for 'x'
 Fx                  search line backward for 'x'
 tx                  search line forward before 'x'
 Tx                  search line backward before 'x'
+CTRL-y              moves screen up one line
+CTRL-e              moves screen down one line
+CTRL-u              moves cursor & screen up ½ page
+CTRL-d              moves cursor & screen down ½ page
+CTRL-b              moves screen up one page, cursor to last line
+CTRL-f              moves screen down one page, cursor to first line
+zz                  shift current line to middle of screen
+z.                  same as zz but also jumps to the first non-black character
+zt                  shift current line to top of screen
+zb                  shift current line to bottom of screen
 
 
 ##############################################################################
@@ -60,8 +68,15 @@ Tx                  search line backward before 'x'
 ma                  make a bookmark named a at the current cursor position
 `a                  go to position of bookmark a
 'a                  go to the line with bookmark a
+`0                  go to the position where Vim was previously exited
+`"                  go to the position when last editing this file
 `.                  go to the line that you last edited
+``                  go to the position before the last jump
+g,                  go to newer position in change list
+g;                  go to older position in change list
 
+# Tip: To jump to a mark you can either use a backtick (`) or an apostrophe (').
+# Using an apostrophe jumps to the beginning (first non-blank) of the line holding the mark.
 
 ##############################################################################
 # INSERT MODE
@@ -70,10 +85,13 @@ ma                  make a bookmark named a at the current cursor position
 
 i                   start insert mode at cursor
 I                   insert at the beginning of the line
+gi                  return to insert mode where you inserted text the last time
+gI                  like "I", but always start in column 1
 a                   append after the cursor
 A                   append at the end of the line
 o                   open (append) blank line below current line
 O                   open blank line above current line
+CTRL-o              Temporarily enter normal mode to issue one normal-mode command(while in insert mode)
 Esc                 exit insert mode
 
 
@@ -84,10 +102,25 @@ Esc                 exit insert mode
 
 r                   replace a single character (does not use insert mode)
 R                   enter Insert mode, replacing characters rather than inserting
-J                   join line below to the current one
+J                   join line below to the current one with one space in between
+gJ                  join line below to the current one without space in between
 cc                  change (replace) an entire line
-cw                  change (replace) to the end of word
-C                   change (replace) to the end of line
+cw                  change (replace) to the end of word (same as ce)
+2cw                 change (replace) repeat cw twice
+ciw                 change (replace) word under the cursor
+caw                 change (replace) word under the cursor and the space after or before it
+ci"                 change (replace) word inside ""
+cit                 change (replace) html tag content
+cat                 change (replace) html tag
+cis                 change (replace) sentence under the cursor
+cas                 change (replace) sentence under the cursor and the space after or before it
+cib                 change (replace) inside a block with ()
+cab                 change (replace) a block with ()
+ciB                 change (replace) inside a block with {}
+caB                 change (replace) a block with {}
+C                   change (replace) to the end of line(same as c$)
+cG                  change (replace) to the end of the file
+cgg                 change (replace) from first line to current line
 ct'                 change (replace) until the ' character (can change ' for any character)
 s                   delete character at cursor and substitute text
 S                   delete line at cursor and substitute text (same as cc)
@@ -102,6 +135,7 @@ guiw                make current word lowercase
 gU$                 make uppercase until end of line
 gu$                 make lowercase until end of line
 >>                  indent line one column to right
+>i{                 indent everything in the {}
 <<                  indent line one column to left
 ==                  auto-indent current line
 ddp                 swap current line with next
@@ -110,6 +144,7 @@ ddkP                swap current line with previous
 :r [name]           insert the file [name] below the cursor.
 :r !{cmd}           execute {cmd} and insert its standard output below the cursor.
 
+# Tip: Instead of b or B one can also use ( or { respectively.
 
 ##############################################################################
 # DELETING TEXT
@@ -118,10 +153,15 @@ ddkP                swap current line with previous
 
 x                   delete current character
 X                   delete previous character
-dw                  delete the current word
+dw                  delete (cut) to the end of word (same as de)
+diw                 delete (cut) word under the cursor
+daw                 delete (cut) word under the cursor and the space after or before it
+dap                 delete (cut) a paragraph
 dd                  delete (cut) a line
-dt'                 delete until the next ' character on the line (replace ' by any character)
-D                   delete from cursor to end of line
+dt'                 delete (cut) until the next ' character on the line (replace ' by any character)
+dG                  delete (cut) to the end of the file
+dgg                 delete (cut) from first line to current line
+D                   delete (cut) from cursor to end of line (same as d$)
 :[range]d           delete [range] lines
 
 
@@ -136,6 +176,10 @@ yy                  yank (copy) a line
 y$                  yank to end of line
 p                   put (paste) the clipboard after cursor/current line
 P                   put (paste) before cursor/current line
+gp                  put (paste) the clipboard after cursor and leave cursor after the new text
+gP                  put (paste) before cursor and leave cursor after the new text
+"+y                 yank into the system clipboard register
+"+p                 paste from the system clipboard register
 :set paste          avoid unexpected effects in pasting
 :registers          display the contents of all registers
 "xyw                yank word into register x
@@ -147,6 +191,12 @@ P                   put (paste) before cursor/current line
 "xgP                just like "P", but leave the cursor just after the new text
 :[line]put x        put the text from register x after [line]
 
+# Tip: if you are using vim extension on vs code, you can enable
+"vim.useSystemClipboard": true
+in setting.json, this will allow to Use system clipboard for unnamed register.
+
+
+
 
 ##############################################################################
 # MACROS
@@ -157,6 +207,7 @@ qa                  start recording macro 'a'
 q                   end recording macro
 @a                  replay macro 'a'
 @:                  replay last command
+@@                  repeat macro
 
 
 ##############################################################################
@@ -172,9 +223,11 @@ CTRL-v              start visual block mode
 O                   move to other corner of block
 aw                  mark a word
 ab                  a () block (with braces)
-ab                  a {} block (with brackets)
+aB                  a {} block (with brackets)
+at                  a block with <> tags
 ib                  inner () block
-ib                  inner {} block
+iB                  inner {} block
+it                  inner <> block
 Esc                 exit visual mode
 
 VISUAL MODE COMMANDS
@@ -194,6 +247,7 @@ v%                  selects matching parenthesis
 vi{                 selects matching curly brace
 vi"                 selects text between double quotes
 vi'                 selects text between single quotes
+gv                  reselect the last selected area
 
 ##############################################################################
 # SPELLING
@@ -240,7 +294,7 @@ set ic                      ignore case: turn on
 set noic                    ignore case: turn off
 :%s/old/new/g               replace all old with new throughout file
 :%s/old/new/gc              replace all old with new throughout file with confirmation
-:argdo %s/old/new/gc | wq   open multiple files and run this command to replace old 
+:argdo %s/old/new/gc | wq   open multiple files and run this command to replace old
                             with new in every file with confirmation, save and quit
 
 
@@ -283,7 +337,6 @@ CTRL-w <            increase window width
 CTRL-w >            decrease window width
 CTRL-w =            equal window
 CTRL-w o            close other windows
-zz                  Centers the window to the current line
 
 
 ##############################################################################
@@ -306,12 +359,14 @@ clast               display the last error
 
 
 %                   show matching brace, bracket, or parenthese
-gf                  edit the file whose name is under or after the cursor
+gf                  edit the file whose name is under the cursor
+gF                  edit the file whose name is under the cursor and jump to the line number
 gd                  when the cursor is on a local variable or function, jump to its declaration
 ''                  return to the line where the cursor was before the latest jump
-gi                  return to insert mode where you inserted text the last time
 CTRL-o              move to previous position you were at
 CTRL-i              move to more recent position you were at
+:set nu             display numbers (short for :set number)
+:set nonu           hide numbers (short for :set nonumber)
 
 
 ##############################################################################
@@ -485,7 +540,7 @@ CTRL-n              jump to the next empty tag / attribute
 
 
 cs'"                change surrounding quotes to double-quotes
-cs(}                change surrounding parens to braces 
+cs(}                change surrounding parens to braces
 cs({                change surrounding parens to braces with space
 ds'                 delete surrounding quotes
 dst                 delete surrounding tags
@@ -593,7 +648,7 @@ jj                  exit insertion mode
 
 <leader>/           clear the search register
 
-<leader>h           toggle hidden characters 
+<leader>h           toggle hidden characters
 
 <leader>W           strip all trailing whitespace
 
@@ -661,5 +716,5 @@ CTRL-y              go to next tag of attribute in sparkup plugin
 <leader>g           toggle Gundo window
 
 IMG<CR>             show image browser to insert image tag with src, width and height
-b                   insert image tag with dimensions from NERDTree 
+b                   insert image tag with dimensions from NERDTree
                     (http://stackoverflow.com/questions/5707925/vim-image-placement)