Thread: The loop does not repeat itself! Why?

I am trying to use a sentinel value to control the loop. However, if I set the sentinel value to be a char, to be entered from keyboard, the loop never repeats itself. But if I set the sentinel value to be an int such as 1, it worked.

The code is as following. Could you please help me out?

Code:

Code:

int main(void)
{
    double miles, kms;
    char sentinel;
    printf("Run the conversion program (y/n)?  ");
    scanf("%c", &sentinel);
    
    while (sentinel=='y')
    {
          printf("Enter the distance in miles>  ");
          scanf("%lf", &miles);
          kms=miles*1.609;
          printf("You traveled %.3f kilometers.\n\n", kms);
          
                printf("Run the conversion program (y/n)?  ");
          scanf("%c", &sentinel);
    }          
    
    return (0);
}

Are you by any chance working with your caps lock turned on... Y (capital) and y (lower) are two different things.

Try it with...

Code:

while (toupper(sentinel) == 'Y')

A little trick with scanf("%c"... is to add a leading space before the % sign as in scanf(" %c"... which tells it to ignore everything before the first visible character.

I added a leading space before % in the scanf statement. Then it worked. But I don't know why.

A whitespace before %c 'eats' all heading whitespaces from your input-line. The first not whitespace without '\n' yourself will be putted in your char variable.