ispunctint

ispunctint is a naming convention encountered in some codebases to refer to a function that tests whether a given integer encodes a punctuation character. It is not a standard or universally defined function across major programming languages, but it is sometimes used to emphasize the use of an int-typed input representing a character.

In languages with a C-like type system, the intended semantics of ispunctint mirror those of the standard ispunct function. A typical (hypothetical) signature would be int ispuntint(int ch); the argument ch is expected to represent a character value, usually in the range of unsigned char or the special value EOF. The function returns a nonzero value if ch is classified as punctuation according to the current locale, and zero otherwise. Because the concept relies on character classification, implementations generally follow the rules of LC_CTYPE or an equivalent locale setting.

Locale and portability considerations are important. In C, the classification of punctuation is locale-sensitive, and the standard ispunct (and any alias like ispuntint) relies on the active locale. Some environments provide a locale-specific variant (for example, ispunct_l) to fix a locale independent of the global setting. Since ispuntint is not part of the C or C++ standard, portability across compilers and libraries is not guaranteed; developers should prefer the standard ispunct or std::ispunct in portable code.

Usage notes and alternatives. In plain C, you would typically use ispunct((unsigned char)ch) to avoid undefined behavior for signed char inputs. For Unicode-aware punctuation, libraries such as ICU or language-specific APIs offer more comprehensive classification beyond the C locale model. In high-level languages, corresponding predicates include Python’s string punctuation checks or Unicode category tests in Java and JavaScript.

See also ispunct, locale, ctype, and Unicode punctuation categories.