[C Programming Language] C Programming Language Main Structure

C Programming Language Main Structures

C Programming Language Elements :

1. Preprocessor directives

Command line which is given instruction to preprocessor.

There are two types of preprocessor : #include and #define.

#include library.h tell preprocessor the library to find the meaning of standard identifier.

#define NAME value tell preprocessor to change every identifier NAME with value before the program was compiled.

Example :

#include stdio.h

#define PI 3.14

2. Comment

Texts which is started with /* or // and finished with */, and contains information about program in order to make the program is understood easily by other programmer. Compiler will ignore comments.

3. Main Function

Syntax :

int main(void)

{

/* main function */

}

Main function is made up from 2 parts :

1. Declaration

2. Executeable Statement

4. Reserved Word and Identifier

Reserved Word :

- word which has special meaning in C and can’t be used again for other.

Example : int, void, double, return, etc.

Identifier :

a. Standard Identifier :

A word which has special meaning in C but it can’t be redefined by user(not recommended).

Example : printf, scanf, etc.

b. User Defined Identifier :

A word which is choosed by user to rename memory cell and user defined operation.

Example : miles, name, x, PI, etc

Expression Evaluation Rule :

1. Parentheses Rule

2. Operator Presedence Rule

From High to Low :

Function calls

!, +, -, & (operator unary)

*, /, %

+, -

<, <=, >=, >

==, !=

&&

||

=

3. Associative Rule

Unary - - > evaluate from Right to Left

Binary - - > evaluate from Left to Right