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

In this example, you will learn to check whether a character entered by the user is an alphabet or not.

To understand this example, you should have the knowledge of following C programming topics:

• C Programming Operators
• C if, if...else and Nested if...else Statement

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

The ASCII value of lowercase alphabets are from 97 to 122. And, the ASCII value of uppercase alphabets are from 65 to 90. Read - Programming language

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

You can also check whether a character is an alphabet or not using isalpha() function.