What are the different categories of functions in C Programming?

Depending on whether arguments are present or not and whether a value is returned or not, functions are categorized into −

• Functions without arguments and without return values

• Functions without arguments and with return values

• Functions with arguments and without return values

• Functions with arguments and with return values

Functions without arguments and without return values

Example

#include<stdio.h>
main (){
   void sum ();
   clrscr ();
   sum ();
   getch ();
}
void sum (){
   int a,b,c;
   printf("enter 2 numbers:\n");
   scanf ("%d%d", &a, &b);
   c = a+b;
   printf("sum = %d",c);
}

Output

Enter 2 numbers:
3
5
Sum=8

Functions without arguments and with return values

Example

#include<stdio.h>
main (){
   int sum ();
   int c;
   c= sum ();
   printf(“sum = %d”,c);
   getch ();
}
int sum (){
   int a,b,c;
   printf(“enter 2 numbers”);
   scanf (“%d%d”, &a, &b);
   c = a+b;
   return c;
}

Output

Enter two numbers 10 20
30

Functions with arguments and without return values

Example

#include<stdio.h>
main (){
   void sum (int, int );
   int a,b;
   printf("enter 2 numbers");
   scanf("%d%d", &a,&b);
   sum (a,b);
   getch ();
}
void sum ( int a, int b){
   int c;
   c= a+b;
   printf (“sum=%d”, c);
}

Output

Enter two numbers 10 20
Sum=30

Functions with arguments and with return values

Example

#include<stdio.h>
main (){
   int sum ( int,int);
   int a,b,c;
   printf("enter 2 numbers");
   scanf("%d%d", &a,&b);
   c= sum (a,b);
   printf ("sum=%d", c);
   getch ();
}
int sum ( int a, int b ){
   int c;
   c= a+b;
   return c;
}

Output

Enter two numbers 10 20
Sum=30