Good written code

Documentation

The comment should disclose things that can not be immediately learned from the code.

There is no "best" style that everyone should be following. Actually, the best style, is a consistent style. If you are part of a team or if you are contributing code to a project, you should follow the existing style that is being used in that project.

functions, you’re essentially obfuscating the application logic from any programmer who reads the code, including yourself.

3. Use Descriptive Names

What does a variable named dxy actually mean? Who knows. You’d probably have to read the entire chunk of code to reverse engineer its meaning. On the other hand, the meaning of a variable like distanceBetweenXY is instantly recognizable.

But, this doesn't necessarily apply to temporary variables. They can be as short as a single character.

Consistent Naming Scheme

mysql_real_escape_string()

MysqlRealEscapeString()

as DIE: Duplication is Evil.

code harder to read and follow.

like a textbook can have thousands of words.
In the same way that a textbook is divided into chapters, a program is divided into related functionality using modules.

which is performed by classes.
The functionality of the class is provided by methods.

In C #, these methods are of two kinds: procedures and functions.

The syntax for declaring a method allows you to uniquely determine what the method is, a procedure or a function.

functions
Return ;
}

Example

What is the class name?
How many methods does the class include?
What are the names of these methods?
What access modifier?
What kind of methods, procedures or functions?
What events correspond to the methods?
What actions are performed when these methods are called?
What parameters?

they can be used in any procedure or subroutine in the program

Local variable declared within subroutines or programming blocks, their local scope means they can only be used within the subroutine or program block they were declared in

functions
Return ;
}

What are the differences?

code
They allow you to create a common routine once and re-use as many times as you want
They allow you to share code with other programs
They allow you to test sub routines independently of the rest of the code