| Item | Value |
| Header file | ctype.h |
| Declaration | int isalnum(int ch); |
| Return | returns nonzero if its argument is either a letter of the alphabet or a digit.
returns zero if the character is not alphanumeric. |
#include <ctype.h>
#include <stdio.h>
int main(void)
{
char ch;
printf(". to exit:");
for(;;) {
ch = getc(stdin);
if(ch == '.')
break;
if(isalnum(ch))
printf("%c is alphanumeric\n", ch);
}
return 0;
}
2 is alphanumeric
1 is alphanumeric
1
1 is alphanumeric
2
2 is alphanumeric
12
1 is alphanumeric
2 is alphanumeric
1
1 is alphanumeric
1
1 is alphanumeric
1
1 is alphanumeric
!
~
.
| 18.1.isalnum |
| 18.1.1. | isalnum |