isalpha() and isdigit() in C/C++

isalpha()

The function isalpha() is used to check that a character is an alphabet or not. This function is declared in “ctype.h” header file. It returns an integer value, if the argument is an alphabet otherwise, it returns zero.

Here is the syntax of isalpha() in C language,

int isalpha(int value);

Here,

value − This is a single argument of integer type.

Here is an example of isalpha() in C language −

Example

 Live Demo

#include<stdio.h>
#include<ctype.h>

int main() {
   char val1 = 's';
   char val2 = '8';

   if(isalpha(val1))
   printf("The character is an alphabet\n");
   else
   printf("The character is not an alphabet\n");

   if(isalpha(val2))
   printf("The character is an alphabet\n");
   else
   printf("The character is not an alphabet");

   return 0;
}

Output

Here is the output

The character is an alphabet
The character is not an alphabet

isdigit()

The function isdigit() is used to check that character is a numeric character or not. This function is declared in “ctype.h” header file. It returns an integer value, if the argument is a digit otherwise, it returns zero.

Here is the syntax of isdigit() in C language,

int isdigit(int value);

Here,

value − This is a single argument of integer type.

Here is an example of isdigit() in C language,

Example

 Live Demo

#include<stdio.h>
#include<ctype.h>

int main() {
   char val1 = 's';
   char val2 = '8';

   if(isdigit(val1))
   printf("The character is a digit\n");
   else
   printf("The character is not a digit\n");

   if(isdigit(val2))
   printf("The character is a digit\n");
   else
   printf("The character is not a digit");

   return 0;
}

Output

Here is the output

The character is not a digit
The character is a digit