Different aspects of function calling

A function may or may not accept any argument. It may or may not return any value. Based on these facts, There are four different aspects of function calls.

• function without arguments and without return value
• function without arguments and with the return value
• function with arguments and without return value
• function with arguments and with the return value

Example of Function without argument and return value

Example 1

#include<stdio.h>  
void printName();  
void main ()  
{  
    printf("Hello ");  
    printName();  
}  
void printName()  
{  
    printf("Javatpoint");  
}  

Output
Hello Javatpoint

Example 2

#include<stdio.h>  
void sum();  
void main()  
{  
    printf("\nGoing to calculate the sum of two numbers:");  
    sum();  
}  
void sum()  
{  
    int a,b;   
    printf("\nEnter two numbers");  
    scanf("%d %d",&a,&b);   
    printf("The sum is %d",a+b);  
}  

Output

Going to calculate the sum of two numbers:
Enter two numbers 10 
24 

The sum is 34


Example for Function without argument and with return value

Example 1:

#include<stdio.h>  
int sum();  
void main()  
{  
    int result;   
    printf("\nGoing to calculate the sum of two numbers:");  
    result = sum();  
    printf("%d",result);  
}  
int sum()  
{  
    int a,b;   
    printf("\nEnter two numbers");  
    scanf("%d %d",&a,&b);  
    return a+b;   
}  

Output

Going to calculate the sum of two numbers:

Enter two numbers 10 
24 
The sum is 34

Example 2: 
program to calculate the area of the square

#include<stdio.h>  
int sum();  
void main()  
{  
    printf("Going to calculate the area of the square\n");  
    float area = square();  
    printf("The area of the square: %f\n",area);  
}  
int square()  
{  
    float side;  
    printf("Enter the length of the side in meters: ");  
    scanf("%f",&side);  
    return side * side;  
}  
Output

Going to calculate the area of the square 
Enter the length of the side in meters: 10 
The area of the square: 100.000000

Example for Function with argument and without return value

Example 1:

#include<stdio.h>  
void sum(int, int);  
void main()  
{  
    int a,b,result;   
    printf("\nGoing to calculate the sum of two numbers:");  
    printf("\nEnter two numbers:");  
    scanf("%d %d",&a,&b);  
    sum(a,b);  
}  
void sum(int a, int b)  
{  
    printf("\nThe sum is %d",a+b);      
}  
Output

Going to calculate the sum of two numbers:

Enter two numbers 10 
24 
The sum is 34

Example 2: 
program to calculate the average of five numbers.

#include<stdio.h>  
void average(int, int, int, int, int);  
void main()  
{  
    int a,b,c,d,e;   
    printf("\nGoing to calculate the average of five numbers:");  
    printf("\nEnter five numbers:");  
    scanf("%d %d %d %d %d",&a,&b,&c,&d,&e);  
    average(a,b,c,d,e);  
}  
void average(int a, int b, int c, int d, int e)  
{  
    float avg;   
    avg = (a+b+c+d+e)/5;   
    printf("The average of given five numbers : %f",avg);  
}  

Output

Going to calculate the average of five numbers:
Enter five numbers:10 
20
30
40
50
The average of given five numbers : 30.000000

Example for Function with argument and with return value

Example 1:

#include<stdio.h>  
int sum(int, int);  
void main()  
{  
    int a,b,result;   
    printf("\nGoing to calculate the sum of two numbers:");  
    printf("\nEnter two numbers:");  
    scanf("%d %d",&a,&b);  
    result = sum(a,b);  
    printf("\nThe sum is : %d",result);  
}  
int sum(int a, int b)  
{  
    return a+b;  
}  
Output

Going to calculate the sum of two numbers:
Enter two numbers:10
20 
The sum is : 30   

Example 2: 
Program to check whether a number is even or odd

#include<stdio.h>  
int even_odd(int);  
void main()  
{  
 int n,flag=0;  
 printf("\nGoing to check whether a number is even or odd");  
 printf("\nEnter the number: ");  
 scanf("%d",&n);  
 flag = even_odd(n);  
 if(flag == 0)  
 {  
    printf("\nThe number is odd");  
 }  
 else   
 {  
    printf("\nThe number is even");  
 }  
}  
int even_odd(int n)  
{  
    if(n%2 == 0)  
    {  
        return 1;  
    }  
    else   
    {  
        return 0;  
    }  
}  
Output

Going to check whether a number is even or odd
Enter the number: 100
The number is even