isspace() Function Example in C Programming

In this source code example, we will see how to use the isspace() function in C programming with an example.

isspace() Function Overview

The isspace() function is provided by the <ctype.h> library in C. This function is designed to check if a given character is a whitespace character. Common whitespace characters include spaces (' '), newlines ('\n'), horizontal tabs ('\t'), vertical tabs ('\v'), form feeds ('\f'), and carriage returns ('\r'). 

Key Points: 

- The function requires the inclusion of the <ctype.h> header. 

- It takes an int (representing the ASCII value of the character) as its argument. 

- Returns a non-zero integer if the character is whitespace, otherwise it returns 0.

Source Code Example

#include <stdio.h>
#include <ctype.h>  // Required for isspace()

int main() {
    char ch;

    printf("Enter a character: ");
    scanf("%c", &ch);

    if (isspace(ch)) {
        printf("The character you entered is a whitespace character.\n");
    } else {
        printf("The character you entered is not a whitespace character.\n");
    }

    return 0;
}

Output

Enter a character:
The character you entered is a whitespace character.
or
Enter a character: A
The character you entered is not a whitespace character.

Explanation

1. At the beginning, required header files are included: stdio.h for standard I/O operations and ctype.h for the isspace() function.

2. In the main() function, a character variable ch is declared.

3. The user is prompted to input a character, which is stored in the ch variable.

4. The isspace() function is used to verify if the given character is a whitespace character.

5. A message is displayed to the user based on whether the character is a whitespace or not.