Decimal digits are any of: 0 1 2 3 4 5 6 7 8 9
For a detailed chart on what the different ctype functions return for each character of the standard ANSII character set, see the reference for the <cctype> header.
In C++, a locale-specific template version of this function (isdigit) exists in header <locale>.
- Character to be checked, casted to an int, or EOF.
Return ValueA value different from zero (i.e., true) if indeed c is a decimal digit. Zero (i.e., false) otherwise.
isdigit is used to check if the first character in str is a digit and therefore a valid candidate to be converted by atoi into an integer value.
|isalnum||Check if character is alphanumeric (function)|
|isalpha||Check if character is alphabetic (function)|