If statement defaults to true

Question

This is a simple process I wrote to try and fix a problem I'm having with other code. Can someone tell me why the if statements are defaulting to true? I read something about scanf requiring a space before the variable, but I did that.

#include <stdio.h>
#include <stdlib.h>

int main(){

char answer;

printf("Y or N ");

scanf(" %c", &answer);

if(answer == 'Y' || 'y'){
   printf("you said yes \n");
}

else if (answer == 'N' || 'n'){
   printf("you said no \n");
}

else {
   printf("sorry, fail \n");
}

return 0;

}

It doesn't matter whether I type N or n or any other character or even number, it spits back "you said yes".

Answer 1

The issue is with the test logic.

if(answer == 'Y' || 'y')

That statement is not working like you might think. The 'y' is netting your program a value of "true" for a lack of a better way of stating it.

What you most likely want is a comparative test like this:

if((answer == 'Y') || (answer =='y'))

Noting that correction, following is a refactored version of your program.

#include <stdio.h>
#include <stdlib.h>

int main()
{

    char answer;

    printf("Y or N ");

    if (scanf("%c", &answer) != 1)
        return 1;

    if((answer == 'Y') || (answer =='y'))
    {
        printf("you said yes \n");
    }

    else if ((answer == 'N') || (answer == 'n'))
    {
        printf("you said no \n");
    }

    else
    {
        printf("sorry, fail \n");
    }

    return 0;

}

Following were some tests at the terminal.

craig@Vera:~/C_Programs/Console/ScanTest/bin/Release$ ./ScanTest 
Y or N U
sorry, fail 
craig@Vera:~/C_Programs/Console/ScanTest/bin/Release$ ./ScanTest 
Y or N Y
you said yes 
craig@Vera:~/C_Programs/Console/ScanTest/bin/Release$ ./ScanTest 
Y or N N
you said no 

To recap, be aware of how logical "and" and "or" operators work within the various tests ("if", "while", and so forth).