strisdigit

Strisdigit is a term used to describe a function or predicate that checks whether a string consists entirely of digit characters. It is not a formal built-in feature in every programming language, but the underlying idea appears in various forms under names such as isdigit, isdecimal, or numeric checks. The concept focuses on character properties rather than interpreting the string as a numeric value.

In Python, the string method isdigit() returns True if all characters in the string are digits and the string is non-empty. This includes Unicode digit characters, not just ASCII 0-9. It returns False for an empty string, and it also returns False if any character is not a digit (for example, a sign, a space, or a decimal point).

In other languages, the same idea is implemented differently. JavaScript commonly uses a regular expression such as /^[0-9]+$/ to test for ASCII digits, though more general Unicode digit checks can be achieved with extended patterns in engines that support Unicode properties. Java and C# provide per-character digit checks (for example, Character.isDigit in Java or Char.IsDigit in C#) applied across every character to determine if the entire string qualifies.

Edge cases include the empty string (usually false), strings containing non-digit characters, and the handling of Unicode digits from other scripts (which may be considered digits in some implementations but not in others). Efficiency typically favors using built-in language facilities that operate on the entire string rather than manual per-character loops.

Common use cases involve input validation, data cleaning, and parsing tasks where a string must contain only numeric digit characters. Related concepts include isdecimal, isnumeric, and regular-expression digit classes.