isalpha in C Programming

The C isalpha function is one of the Standard Library Function, which is used to check the given character is an alphabet or not.

In this article we will show you, How to use isalpha in C Programming language with example. Before we get into the example, the basic syntax of the isalpha in C language is as shown below.

C isalpha Function syntax

The below isalpha function will accept the single character as the parameter, and check whether the given character is an alphabet or not.

isalpha(char)

isalpha in C Programming Example

The isalpha method is used to find the given character is an alphabet or not. This program allows the user to enter any character, and check whether the character is between A to Z, or a to z using the isalpha function.

//Example for isalpha in C Programming
#include <stdio.h>
#include <ctype.h>

int main()
{
    char ch;
    printf("Please Enter Any Valid Character: \n");
    scanf("%c", &ch);

    if(isalpha(ch))
    {
      printf("\n You have entered an Alphabet");         
    }
    else
    {
      printf("\n %c is not an Alphabet", ch);
      printf("\n I request you to enter Valid Alphabet");	
    }
}

OUTPUT

Let me enter the Uppercase letter

ANALYSIS

First we declared a character variable called ch

char ch;

The following statement will ask the user to enter any character. And then we are using the scanf to assign the user entered character to ch variable

printf("Please Enter Any Valid Character: \n");
scanf("%c", &ch);

In this next line, we added the If Statement to check whether the character is between ‘A’ and ‘Z’ using C isalpha function. If the condition is True then the following statement will be printed

printf("\n You have entered an Alphabet");

If the above condition is FALSE then the given character is not Alphabet. So, it will print below statements

printf("\n %c is not an Alphabet", ch);
printf("\n I request you to enter Valid Alphabet");

Above code will definitely check whether the given character is an alphabet or not, but what if, we enter the numeric value

TIP: Please refer C Program to check whether the Character is Alphabet or Not article to understand, How to check whether the character is alphabet without using the isalpha function.