#include <stdio.h>

void main ()
{
    printf ("PRN-2301106083");
    int a, b, r;
    char s;
    printf ("\n\nEnter the number 'A':");
    scanf ("%d", &a);
    printf ("\nEnter the number 'B'");
    scanf ("%d",&b);
    printf ("\nEnter the operator '+,-,*,/,%':");
    scanf ("%c", &s);
    
    switch (s)
    {
        case '+':
        printf ("\nYou have entered addition!");
        r=a+b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '-':
        printf ("\nYou have entered substraction!");
        r=a-b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '*':
        printf ("\nYou have entered multiplication!");
        r=a*b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '/':
        printf ("\nYou have entered division!");
        r=a/b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '%':
        printf ("\nYou have entered modulus!");
        r=a%b;
        printf ("\nThe output is: %d", r);
        break;
        
        default:
        printf ("\nInvalid Choice")
    }
}

It will straight away print the last printf’s Invalid Choice even when I have not enter the operator from the previous commmand.If anyone can pls send the corrected code or point out what’s wrong then pls do.

>Solution :

The %c conversion specifier won’t skip any leading whitespace automatically. One solution to this problem is to put a space before the conversion specifier in the format string, which "tells" scanf to skip leading whitespace:

scanf(" %c", &s);

Finally, with this fix, your code should look like this:

#include <stdio.h>

void main ()
{
    printf ("PRN-2301106083");
    int a, b, r;
    char s;
    printf ("\n\nEnter the number 'A':");
    scanf ("%d", &a);
    printf ("\nEnter the number 'B'");
    scanf ("%d",&b);
    printf ("\nEnter the operator '+,-,*,/,%':");
    scanf (" %c", &s);
    
    switch (s)
    {
        case '+':
        printf ("\nYou have entered addition!");
        r=a+b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '-':
        printf ("\nYou have entered substraction!");
        r=a-b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '*':
        printf ("\nYou have entered multiplication!");
        r=a*b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '/':
        printf ("\nYou have entered division!");
        r=a/b;
        printf ("\nThe output is: %d", r);
        break;
        
        case '%':
        printf ("\nYou have entered modulus!");
        r=a%b;
        printf ("\nThe output is: %d", r);
        break;
        
        default:
        printf ("\nInvalid Choice");
    }
}