printf("Enter a character: ");
if( (c>='a' && c<='z') || (c>='A' && c<='Z'))
printf("%c is an alphabet.",c);
printf("%c is not an alphabet.",c);
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.
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, 'z' is used instead of 122, '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.