isdigit(3) [netbsd man page]
ISDIGIT(3) BSD Library Functions Manual ISDIGIT(3) NAME
isdigit -- decimal-digit character test LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <ctype.h> int isdigit(int c); DESCRIPTION
The isdigit() function tests for any decimal-digit character. RETURN VALUES
The isdigit() function returns zero if the character tests false and returns non-zero if the character tests true. SEE ALSO
ctype(3), isalnum(3), isalpha(3), isascii(3), isblank(3), iscntrl(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3), isxdigit(3), stdio(3), toascii(3), tolower(3), toupper(3), ascii(7) STANDARDS
The isdigit() function conforms to ANSI X3.159-1989 (``ANSI C89''). CAVEATS
The argument to isdigit() must be EOF or representable as an unsigned char; otherwise, the behavior is undefined. See the CAVEATS section of ctype(3) for more details. BSD
April 17, 2008 BSD
Check Out this Related Man Page
CTYPE(3) BSD Library Functions Manual CTYPE(3) NAME
isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isblank, toupper, tolower, -- character classification and mapping functions LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <ctype.h> isalpha(int c); isupper(int c); islower(int c); isdigit(int c); isxdigit(int c); isalnum(int c); isspace(int c); ispunct(int c); isprint(int c); isgraph(int c); iscntrl(int c); isblank(int c); toupper(int c); tolower(int c); DESCRIPTION
The above functions perform character tests and conversions on the integer c. See the specific manual pages for information about the test or conversion performed by each function. EXAMPLES
To print an upper-case version of a string to stdout, the following code can be used: const char *s = "xyz"; while (*s != '