There are some predefined functions available in "ctype.h" library for analyzing the character input and converting them.
Analysis Functions
The character analysis functions are listed below −
| Function | Checks whether entered character is |
|---|---|
| isalpha | An alphabet (or) not |
| isdigit | A digit (or) not |
| isspace Q | A space, a newline (or) tab |
| ispunct ( | A special symbol (or) not |
| islower | A lower case letter of alphabet |
| isupper Q | An upper case letter of alphabet |
| isalphanumeric | An alphabet/digit or not |
Converting Functions
The converting functions are listed below −
| Function | Conversion |
|---|---|
| tolower() | Converts an upper case alphabet to lower case |
| toupper Q | Converts a lower case alphabet to upper case |
Program
Following is the C program for character analysis and conversion functions which are used to test the character type −
#include <stdio.h>
#include <ctype.h>
main(){
char character;
printf("Press any key digit or alphabet\n");
character = getchar();
if (isalpha(character) > 0)
printf("The character is a letter.");
else
if (isdigit (character) > 0)
printf("The character is a digit.");
else
printf("The character is not alphanumeric.");
}Output
When the above program is executed, it produces the following result −
Run 1: Press any key digit or alphabet 3 The character is a digit. Run 2: Press any key digit or alphabet G The character is a letter. Run 3: Press any key digit or alphabet & The character is not alphanumeric.