C Program to check character is alphabet or number or a Special character
Check Character Program :
Write a C Program to Check character is alphabet or number or a special character. The program should accept a character from the user and detect if the given character is Alphabet or Digit or Special Character.
Here are the example input and excepted output of the program.
Example 1
Input:
|
1 |
Enter character to test : 4 |
Output:
|
1 |
4 is Digit.. |
Example 2:
Input:
|
1 |
Enter character to test : M |
Output:
|
1 |
M is alphabet.. |
Example 3:
Input:
|
1 |
Enter character to test : & |
Output:
|
1 |
& is special symbol.. |
Algorithm – Check character is alphabet or Digit or a Special character :
Here is the algorithm of the character detection program.
- The program should take one character as input from the user. We are going to store it in the c varaible.
- Then We need to check if the given character is Alphabet, Digit, or a special character.
- We are going to use the
ctype.h library for checking the character. The
ctype.h library contains the functions like
isalpha() and
isdigit().
- The isalpha(ch) function takes Integer (which will be converted to ASCII value upon passing ) as input. Returns a non-zero integer value if the given character ch is Alphabet.
- Similarly, The isdigit(ch) function takes Integer as input. and Returns the non-zero Integer value if the given value is a digit.
- By using the isalpha() and isdigit() functions we will check if the given input is an alphabet or Digit.
- If the given number is neither alphabet nor Digit, Then it must be a Special character.
Check character is alphabet or number or a Special character Program:
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#include<stdio.h> #include<ctype.h>  int main() {     // Create a character variable 'ch'     char ch;      // Take the input character from user     // Store it in the 'ch' variable     printf("Enter character to test : ");     scanf(" %c", &ch);      // We will check if the given character 'ch' is alphabet     // by using the 'isalpha()' function     // The 'isalpha()' function is available in the ctype.h library     // 'isalpha()' function takes character as input and return 'true' if it is alphabet.     if(isalpha(ch))        //is alpha available in ctype.h     {         printf("%c is alphabet..\n",ch);     }     else if(isdigit(ch))     {         // The 'isdigit()' function also available in the 'ctype.h' library.         // 'isdigit()' function takes one character as input and returns true if the given character is Digit.         printf("%c is Digit..\n",ch);     }     else     {         // If the given character is not a 'alhpabet' and 'Digit' then it must be special character.         printf("%c is special symbol..\n",ch);     }      return 0; } |
Program Output:
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// Compilling the program using the gcc compiler venkey@venkey$ gcc check-alpha.c  // Run the Executable file venkey@venkey$ ./a.out Enter character to test : 1 1 is Digit..  venkey@venkey$ ./a.out Enter character to test : A A is alphabet..  venkey@venkey$ ./a.out Enter character to test : v v is alphabet..  venkey@venkey$ ./a.out Enter character to test : ? ? is special symbol..  venkey@venkey$ ./a.out Enter character to test : * * is special symbol..  venkey@venkey$ ./a.out Enter character to test : Q Q is alphabet..  venkey@venkey$ ./a.out Enter character to test : 4 4 is Digit.. venkey@venkey$ |
Method 2: character is alphabet or number or a special character Program:
In the previous method, We used the in-built functions like isalpha and isdigit. In this method, we are going to check the alphabet and digit manually.
Logic to check the alphabet:
We are going to compare the ASCII characters. To be an alphabet, the given character must be in between the a and z ( upper case and Lower case). So we can use the following logic to check the alphabet
(ch >= ‘a’ && ch <= ‘z’) || (ch >= ‘A’ && ch <= ‘Z’)
If the above logic returns True, Then the given number is Alphabet.
Logic to check the Digit:
Here also we will compare the ASCII character. Use the following condition to check if the character ch is Digit.
ch >= ‘0’ && ch <= ‘9’
If this condition is True, Then input character ch is Digit.
Check character C Program:
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#include<stdio.h>  int main() {     // Create a character variable 'ch'     char ch;      // Take the input character from user     // Store it in the 'ch' variable     printf("Enter character to test : ");     scanf(" %c", &ch);      // We will check if the given character 'ch' is alphabet     // Manually comparing the 'ch' with ASCII characters     // if the 'ch' is betwen the ASCII character 'a' and 'z' (Lower and Upper Case)     if( (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))          {         printf("%c is alphabet..\n",ch);     }     else if(ch >= '0' && ch <= '9' )     {         // Manullay comparing the ASCII characters         // 'ch' should be greater than or equal to  '0' and lessthan or equal to 9 to be Digit         printf("%c is Digit..\n",ch);     }     else     {         // If the given character is not a 'alhpabet' and 'Digit' then it must be special character.         printf("%c is special symbol..\n",ch);     }      return 0; } |
Program Output:
We used GCC compiler to compile and run the program on Linux operating system. Learn more about the C Program compilation in following article
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$ gcc alpha-digit.c $ ./a.out Enter character to test : M M is alphabet.. $ ./a.out Enter character to test : v v is alphabet.. $ ./a.out Enter character to test : 8 8 is Digit.. $ ./a.out Enter character to test : 0 0 is Digit.. $ ./a.out Enter character to test : ] ] is special symbol.. $ ./a.out Enter character to test : ? ? is special symbol.. $ |
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