C isalpha()

The isalpha() function defined in the ctype.h header file. It helps to check the specified character is alphabet(a to z and A-Z)  or not.


int isalpha(int argument); #where argument will be a character
 

isalpha() Parameters:

The isalpha() function takes a single parameter and is in the form of an integer and the return value should be an integer. When a character is passed it is converted into the integer value corresponding to its ASCII value.

Parameter Description Required / Optional
argument  The character to be checked Required

isalpha() Return Value

 If the given character is an alphabet, isalpha() returns a non-zero integer else zero.When an alphabetic character is passed we will get a different non-zero integer.

Input Return Value
Zero If the parameter isn't an alphabet
Non zero number If the parameter is an alphabet

Examples of isalpha() method in Python

Example 1: Working of isalpha() function in C


#include <stdio.h>
#include <ctype.h>
int main()
{
    char ch;
    ch = 'A';
    printf("\nIf uppercase alphabet is passed: %d", isalpha(ch));

    ch = 'a';
    printf("\nIf lowercase alphabet is passed: %d", isalpha(ch));

    ch='+';
    printf("\nIf non-alphabetic character is passed: %d", isalpha(ch));

    return 0;
}

Output:


If uppercase alphabet is passed: 1
If lowercase alphabet is passed: 2
If non-alphabetic character is passed: 0

Example 2: How isalpha() function works in C?


#include <stdio.h>
#include <ctype.h>
int main()
{
    char ch;

    printf("Please enter a character: ");
    scanf("%c", &ch;);

    if (isalpha(ch) == 0)
         printf("The given %c is not an alphabet.", ch);
    else
         printf("The given %c is an alphabet.", ch);

    return 0;
}

Output:


Please enter a character: 10
The given 10 is not an alphabet.