### C Library Functions: Character Testing

Function | Header File | Description
isalnum | ctype.h | Tests for alphanumeric characters.
isalpha | ctype.h | Tests for alphabetic characters.
isascii | ctype.h | Tests if an integer is within the ASCII range.
isblank | ctype.h | Tests for the blank character attribute.
iscntrl | ctype.h | Tests for control characters.
_iscsym | ctype.h | Tests if a character is alphabetic or an underscore.
_iscsymf | ctype.h | Tests if a character is alphabetic, a digit, or an underscore.
isdigit | ctype.h | Tests for decimal digits.
isgraph | ctype.h | Tests for printable characters excluding the space.
islower | ctype.h | Tests for lowercase letters.
isprint | ctype.h | Tests for printable characters including the space.
ispunct | ctype.h | Tests for printable characters excluding the space.
isspace | ctype.h | Tests for white-space characters.
isupper | ctype.h | Tests for uppercase letters.
iswalnum | wctype.h | Tests for alphanumeric wide characters.
iswalpha | wctype.h | Tests for alphabetic wide characters.
iswblank | wctype.h | Tests a wide character for the blank character attribute.
iswctype | wctype.h | Tests a wide character for a specified property.
iswdigit | wctype.h | Tests wide characters for decimal digits.
iswgraph | wctype.h | Tests for printable wide characters excluding the space.
iswlower | wctype.h | Tests wide characters for lowercase letters.
iswprint | wctype.h | Tests for printable wide characters including the space.
iswpunct | wctype.h | Tests for printable wide characters excluding the space.
iswspace | wctype.h | Tests for white-space wide characters.
iswupper | ctype.h | Tests wide characters for uppercase letters.
isxdigit | ctype.h | Tests for hexadecimal digits.
iswxdigit | wctype.h | Tests wide characters for hexadecimal digits.
wctype | wchar.h | Returns the handle for a character class or property.
wcwidth | wchar.h | Determines number of display positions required to display a given wide character.

Alphabetical Listing of IBM C and C++ Compilers Functions and Macros