Function with no arguments & no return value

Input:

#include <stdio.h>

void checkPrimeNumber();

int main()

{

checkPrimeNumber();    // argument is not passed

return 0;

}

void checkPrimeNumber()   // return type is void means it doesn't return any value

{

int n, i, flag = 0;

printf("Enter a positive integer: ");

scanf("%d",&n);

for(i=2; i <= n/2; ++i)

{

if(n%i == 0)

{

flag = 1;

}

}

if (flag == 1)

printf("%d is not a prime number.", n);

else

printf("%d is a prime number.", n);

}

Output:

Enter a positive integer: 4

4 is not a prime number

-----------------------------------------------------------------------------------

Enter a positive integer: 5

5 is a prime number

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The checkPrimeNumber() function takes input from the user, checks whether it is a prime number or not, and displays it on the screen.

The empty parentheses in checkPrimeNumber(); statement inside the main() function indicates that no argument is passed to the function.

The return type of the function is void. Hence, no value is returned from the function.

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