C Program to check character is alphabet or digit

C program to check whether given character is alphabet or digit

By Ahmad Irshad | C Programming Exercises and Solutions > If...Else  

Write a C program to input a character from user and check whether a given character is alphabet or digit using if...else...if statement. Have a look at the below step by step logic to check whether a given character is alphabet or digit.

Example:

1. INPUT
2. 
   
3. Enter a character: L
4. 
   

  OUTPUT

L is a alphabet character.

Required knowledge for this exercise

Input / output | Variables | Data types | If-else | Relational operator | Logical operator | Arithmetic operator

Logic to check whether a given character is alphabet or digit:

In C programming, every character has an unique ASCII value (An integer value between 0 to 127 is known as ASCII value).Which is used to represent a character in memory. In memory every character is stored as an integer. 

 

Now let's see the below step by step logic to check given character is alphabet or digit.

1) Input a character from user and store it in variable ch using scanf() fucntion.

2) Check the below conditions:

1.  if((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) then, it is an   ALPHABET.
2.  if ((ch >= '0' && ch <= '9') then, it is a DIGIT.

 Otherwise neither ALPHABET nor DIGIT

Program to check whether a character is alphabet or digit using if...else...if: 

1. /* C program to check whether a character is alphabet or digit */ #include <stdio.h> int main() { char ch; /* Input a character from user */ printf("Please Enter any character: "); scanf("%c", &ch); if((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) { printf("\n%c is an Alphabet.", ch); } else if ((ch >= '0' && ch <= '9') { printf("\n%c is a digit.", ch); }
2. else { printf("\n%c neither Alphabet nor digit.", ch); } return 0; }

You can also use the ASCII value to check alphabets character. Since we know that, every character has an unique ASCII value (An integer value between 0 to 127). For example: ASCII value of a=97, z=122, A=65, Z=90 and 0=48, 9=57.

Have a look at the below program to check whether a character is alphabet or not using ASCII Value: 

1. /* C program to check whether a character is alphabet, digit or not */ #include <stdio.h> int main() { char ch; /* Input a character from user */ printf("Please Enter any character: "); scanf("%c", &ch); if((ch >= 97 && ch <= 122) || (ch >= 65 && ch <= 90)) { printf("\n%c is an Alphabet.", ch); } else if ((ch >= 48 && ch <= 57) { printf("\n%c is a digit." ch); }
2. else { printf("\n%c neither Alphabet nor digit.", ch); } return 0; }

Output:

1. Please Enter any character: L
2.  L is an alphabet.

1. 
   
2. Please Enter any character: 10
3. 10 is  a digit.

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