test if a char is a digit or nondigit

[clarineterr]

is there a way to check if a char is a digit (ie a number between 0 and 9) or a letter or something else?

[Wizard]

char foo = '5'; // for example
if (foo >= '0' && foo <= '9')
{ // foo is a number
}
if (foo >= 'a' && foo <= 'z')
{ // foo is a lowercase letter
}
if (foo >= 'A' && foo <= 'Z')
{ // foo is an uppercase letter
}

[Alvaro]

You can use isdigit(), isalpha(), etc., from <cctype>.