Syntax/Format of C program

C Programs

A C program can vary from 3 lines to millions of lines and it should be written into one or more text files with extension ".c"; for example, hello.c. You can use "vi", "vim" or any other text editor to write your C program into a file.

Before we study the basic building blocks of the C programming language, let us look at a bare minimum C program structure so that we can take it as a reference in the upcoming chapters.

    Syntax/Format of simple C program

main ()  <---------------------Function name
 {  <------------------------------Start of program
        ........
        ........  <-------------------Program statement
        ........
 }  <------------------------------End of program

    Hello World Example

A C program basically consists of the following parts −
• Preprocessor Commands
• Functions
• Variables
• Statements & Expressions
• Comments
Let us look at a simple code that would print the words "Hello World" −

#include <stdio.h>
int main()
 {
   /* my first program in C */
   printf("Hello, World! \n");

   return 0;
}

Let us take a look at the various parts of the above program −
• The first line of the program #include <stdio.h> is a preprocessor command, which tells a C compiler to include stdio.h file before going to actual compilation.
• The next line int main() is the main function where the program execution begins.
• The next line /*...*/ will be ignored by the compiler and it has been put to add additional comments in the program. So such lines are called comments in the program.
• The next line printf(...) is another function available in C which causes the message "Hello, World!" to be displayed on the screen.
• The next line return 0; terminates the main() function and returns the value 0.