C Programming Fundamentals - structure of a c program

structure of a c program 

A C program basically has the following form:

1.Preprocessor Commands

2.Functions

3.Variables

4.Statements & Expressions

5.Comments

The following program is written in the C programming language. Open a text file hello.c using vi editor and put the following lines inside that file.

#include <stdio.h>

int main()

{

   /* My first program */

   printf("This is Sai Teja Nagamothu\n");

      return 0;

}

Output: This is Sai Teja Nagamothu 

Preprocessor Commands: These commands tells the compiler to do preprocessing before doing actual compilation. Like #include <stdio.h> is a preprocessor command which tells a C compiler to include stdio.h file before going to actual compilation. You will learn more about C Preprocessors in C Preprocessors session.

Functions: are main building blocks of any C Program. Every C Program will have one or more functions and there is one mandatory function which is called main() function. This function is prefixed with keyword int which means this function returns an integer value when it exits. This integer value is retured using return statement.

The C Programming language provides a set of built-in functions. In the above example printf() is a C built-in function which is used to print anything on the screen. Check Builtin function section for more detail.

You will learn how to write your own functions and use them in Using Function session.

Variables: are used to hold numbers, strings and complex data for manipulation. You will learn in detail about variables in C Variable Types.

Statements & Expressions : Expressions combine variables and constants to create new values. Statements are expressions, assignments, function calls, or control flow statements which make up C programs.

Comments: are used to give additional useful information inside a C Program. All the comments will be put inside /*...*/ as given in the example above. A comment can span through multiple lines.