Structure of c program
Every C program contains a number of several building blocks known as functions. Each function of it performs task independently. A function is subroutine that may consist of one or more statements.
Example:
Include header file section
Global Declaration section
void main (void) /*main function */
{
Declaration part
Executable part
}
user-defined functions
{
}
Include header file section
- C program depends upon some header files for function definition that are used in a program. Each header file by default is extended with .h.
- The file should be included using #include directive as given below.
Example:
#include or #include “stdio.h.”
Global declaration
- This section declares some variables that are to be used in more than one function. These variables are known as global variables.
- This section must be declared outside of all the functions.
Function main(void)
- Program written in C language contains a void main(void) function. Arguments, if needed, are specified within the parentheses following the function name main.
- Here in this program void enclosed within a bracket indicates that no arguments are passed to the main function. The keyword void before main returns nothing.
Declaration part
- The declaration part declares the entire variables that are used in executable part.
- The initialization of variables is also done in this section.
- The initialization means providing initial value to the variables.
Executable part
- This part contains the statements following the declaration of the variables. It also contains a set of statements or a single statement.
User-defined function
- The functions defined by the user are called user-defined functions. These functions are generally defined after the main() function.
- They can also be defined before main() function. This portion is not compulsory.
Comments
- Comments are not necessary in the program. However, to understand the flow of programs, programmers can include comments in the program.
- Comments should be placed between the delimiters /* and */. The compiler does not execute comments.