C Program to Check Whether a Character is an Alphabet or not

In C programming, a character variable holds an ASCII value (an integer number between 0 and 127) rather than that character itself.

The ASCII value of the lowercase alphabet is from 97 to 122. And, the ASCII value of the uppercase alphabet is from 65 to 90.

If the ASCII value of the character entered by the user lies in the range of 97 to 122 or from 65 to 90, that number is an alphabet.

Program to Check Alphabet

#include <stdio.h>
int main() {
    char c;
    printf("Enter a character: ");
    scanf("%c", &c);

    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
        printf("%c is an alphabet.", c);
    else
        printf("%c is not an alphabet.", c);

    return 0;
}

Output

Enter a character: *
* is not an alphabet

In the program, 'a' is used instead of 97 and 'z' is used instead of 122. Similarly, 'A' is used instead of 65 and 'Z' is used instead of 90.

if (isalpha(c))
    printf("%c is an alphabet.", c);
else
    printf("%c is not an alphabet.", c);