The isalnum() function in C language

The featureisalnum()used to check if a character is alphanumeric. It returns a non-zero value if the character is alphanumeric, indicating a letter or number, otherwise it returns zero. Declared in the "ctype.h" header file.

This isisalnum()C Language Syntax,

int isalnum(int character);

Here,

Character-the character to be checked.

This isisalnum()C Language Example,

Example

#include<stdio.h>
#include<ctype.h>
int main() {
　　　char val1　= ';s';
　　　char val2　= ';'8';
　　　char val3　= '$';
　　　if(isalnum(val1))
　　　printf("The character is alphanumeric\n");
　　　else
　　　printf("The character is not alphanumeric\n");
　　　if(isalnum(val2))
　　　printf("The character is alphanumeric\n");
　　　else
　　　printf("The character is not alphanumeric");
　　　if(isalnum(val3))
　　　printf("The character is alphanumeric\n");
　　　else
　　　printf("The character is not alphanumeric");
　　　return 0;
}

Output Result

The character is alphanumeric
The character is alphanumeric
The character is not alphanumeric

In the above program, three char type variables are declared and initialized with values. By usingisalnum()The function checks whether these variables are alphanumeric values.

if(isalnum(val1))
printf("The character is alphanumeric\n");
else
printf("The character is not alphanumeric\n");