Question

Is there an easy way to check for digits 0-9 with a switch statement? I’m writing a program to check for certain characters as well as digits. Like checking for ‘\0’, ‘F’ or ‘f’, and was wondering if there was also a way to check for 0-9 in a similar fashion. I know I can write a program to return true or false if a character is a digit 0-9, but wasn’t sure how to use that with one of the cases in a switch statement. Like if I had:

const int lowerBound = 48;
const int upperBound = 57;

bool isDigit(char *digit)
{
    if (*digit >= lowerBound && *digit <= upperBound) {
        return true;
    }
    else {
        return false;
    }
}

how I can go

switch (*singleChar) {
    case(???):
}

Answer 1

I would probably write the switch statement for the particular letters (´f´, ´F´…) and add the condition in the else block.

switch ( ch ) {
case 'f': // ...
   break;
case 'F': // ...
   break;
default:
   if ( isDigit(ch) ) {
   }
};

(Also note that there is a standard isdigit function from standard C in header <cctype> and another in <locale> that takes a locale as parameter and performs checks based on that locale)