Structure of a C Program

Basically the structure of a C program consists of four modules.

1. Preprocessor Directives (Includes, Macros)
2. Global declarations (Functions, Variables..)
3. The main function (Program execution starts here..)
4. User-defined functions (Option to the user)

First C Program

      #include<stdio.h>
      main() // First function invoked by the compiler
      {
         printf("WELCOME TO C PROGRAMMING");//To display the things in double quotes
      }

Output

            WELCOME TO C PROGRAMMING

Program description

• The first line of the program, which tells a compiler to include header files for library functions.
• In the main function, the program execution will begin.
• The print(...) is a function available in C is to print "Welcome to c programming" on the screen.
• The comment symbol /*....*/ will be ignored by the compiler.
• Comments can be inserted anywhere in the C program.
• Nested comments are ignored by the compiler.
• Braces are generally used for grouping of statements.
• Generally, all letters are written in lowercase letters.
• Every C statement ends with a semicolon.

Compile and execute c program

• Open text editor
• Open the file name pg1.c and paste the above program into it and save the file(ESC button+w+q)
• for compile type cc pg1.c
• for output type ./a.out