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Test a character to see if it's alphanumeric
#include <ctype.h>
int isalnum( int c );
- c
- The character you want to test.
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
The isalnum() function tests if the argument c
is an alphanumeric character (a to z, A
to Z, or 0 to 9).
An alphanumeric character is any character for which
isalpha() or
isdigit() is true.
Nonzero if c is a letter or decimal digit; otherwise, zero.
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
int main( void )
{
if( isalnum( getchar() ) ) {
printf( "That's alpha-numeric!\n" );
}
return EXIT_SUCCESS;
}
ANSI,
POSIX 1003.1
Safety: | |
Cancellation point |
No |
Interrupt handler |
Yes |
Signal handler |
Yes |
Thread |
Yes |
The result is valid only for char arguments and
EOF.
isalpha(),
iscntrl(),
isdigit(),
isgraph(),
islower(),
isprint(),
ispunct(),
isspace(),
isupper(),
iswalnum()
isxdigit(),
tolower(),
toupper()
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