The isalnum() function defined in the ctype.h header file. It helps to check the specified character is alphanumeric or not. The character is said to be alphanumeric it will be an alphabet or number.
int isalnum(int argument); #where argument will be a character
The isalnum() function takes a single parameter.
Parameter | Description | Required / Optional |
---|---|---|
argument | The character to be checked | Required |
The return value is either 1 or 0.
Input | Return Value |
---|---|
argument is an alphanumeric | 1 |
argument is neither an alphabet nor a digit | 0 |
#include <stdio.h>
#include <ctype.h>
int main()
{
char ch;
int output;
ch = '10';
output = isalnum(ch);
printf("If %c is passed, return value is %d\n", ch, output);
ch = 'A';
output = isalnum(ch);
printf("If %c is passed, return value is %d\n", ch, output);
ch = 'B';
output = isalnum(ch);
printf("If %c is passed, return value is %d\n", ch, output);
ch = '+';
output = isalnum(ch);
printf("If %c is passed, return value is %d\n", ch, output);
return 0;
}
Output:
If 10 is passed, return value is 1 If A is passed, return value is 1 If B is passed, return value is 1 If + is passed, return value is 0
#include <stdio.h>
#include <ctype.h>
int main()
{
char ch;
printf("Enter a character: ");
scanf("%c", &ch);
if (isalnum(ch) == 0)
printf("The given %c is not an alphanumeric character.", ch);
else
printf("The given %c is an alphanumeric character.", ch);
return 0;
}
Output:
Enter a character: 0 The given 0 is an alphanumeric character.