C tutorials Structure in C

Basic Structure of C:

A C program Basically builds on the following parts:

  v  Preprocessor Commands

  v  Functions

  v  Variables

  v  Statements & Expressions

     v  Comments

Now write your first program

#include<stdio.h>

Int main()

{

Printf(“Hello World”);

Return 0;

}

Output:

Hello World

Structure:

Preprocessor Directions

Global Declarations

Main()

{

Local Declaration;

Statements;

}

Function1()

{

Local Declaration;

Statements;

}

Function2()

{

Local Declaration;

Statements;

}

Ø  The first line of the program #include<stdio.h> is a preprocessor command, which tells a compiler to include stdio.h file before going to actual compilation.

Ø  The next line int main() is the main function where the program execution starts.

Ø  The line/*..*/ will be avoided by the compiler and it has been put to add additional comments in the program. Such lines are named comments in the program.

Ø  The next line printf(“…”); is another function in C which causes the massage. “Programming C” to be displayed Programming C

Ø  The next line return 0; terminates the main() function and return the value 0.

Compile and execute C program:

Let us see how to save the source code in a file and how to compile and following are the simple steps:

Ø  Open a text editor and add the above mention codes.
Ø  Save the file as hello.c.
Ø  Open a command prompt and go to the directory where you saved the file.
Ø  Type gcc hello.c and press enter to compile your code.
Ø  If there are no errors in your code, the command prompt will take you to the next line and would generate a.out executable file.
Ø  Now, type a.out to execute your program.
Ø  Output Programming C is shown on the display

 $gcc programming.c

$-/a-out

Programming C

Make sure the gcc compiler is in your path and that you are running it in the directory containing the source file programming.c