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isalnum |
Portability: | ISO/ANSI C conforming, UNIX compatible |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
CAUTIONS | |
EXAMPLE | |
RELATED FUNCTIONS | |
SEE ALSO |
SYNOPSIS |
#include <ctype.h> int isalnum(int c);
DESCRIPTION |
isalnum
tests an integer value to determine whether it is an alphabetic (uppercase
or lowercase) or numeric character.
RETURN VALUE |
isalnum
returns 0 if the character is not alphanumeric, or a nonzero value if it is
alphanumeric. If the argument is
EOF
,
0 is returned.
CAUTIONS |
The effect of
isalnum
on a noncharacter argument other than
EOF
is undefined. Do not assume that
isalnum
returns either 0 or 1.
EXAMPLE |
#include <ctype.h> #include <stdio.h> #define MAXLEN 40 main() { char id[MAXLEN+1]; int i; char *text; char input[MAXLEN]; puts("Enter a string of characters (40 at most)."); text = gets(input); puts("Initial alphanumeric characters you entered are:"); for (i = 0; i < MAXLEN && isalnum(text[i]); i++) { id[i] = text[i]; putc(id[i]); } id[i] = '\0'; putc('\n'); }
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