isalnum in c

What is isalnum in c programming?

isalnum in c checks the input parameter is alphanumeric or not.

This function is defined in ctype.h header file.

This function returns non-zero digit if passed character is decimal value otherwise zero.

Prototype

int isalnum(int a);

Parameter

This function takes character as input parameter and converts it into ASCII value.

Return value

This function returns non-zero value if passed character is alphanumeric otherwise zero.

---

Example program for isalnum function in c

#include<stdio.h>
#include<ctype.h>
int main()
{
  int x='2';
  int b='\';
  printf("\n\n\tThe passed value is %d \n",isalnum(x));
  printf("\tThe passed value is %d \n",isalnum(b));
  return 0;
}

Code explanation

isalnum function is called to check whether the passed character is an alphanumeric character or not. The result is being printed onto the console.

isalnum() Man page

---

Difference between isalnum and isalpha in c

isalnum function checks the input parameter is alphanumeric or not. isalpha function checks the passed parameter is alphabet or not.

Prototypes are as follows

int isalnum(int a);

int isalpha(int a);

isalnum	isalpha
Checks the input parameter is alphanumeric or not.	Checks the passed parameter is alphabet or not.
int isalnum(int a);	int isalpha(int c);

---

People also ask for

---