#include <stdio.h>
#include <ctype.h>

int main() {
    char c = ' ';
    if (isspace(c)) {
        printf("The character is a whitespace character.\n");
    } else {
        printf("The character is not a whitespace character.\n");
    }
    return 0;
}
In this example, the isspace() function is used to check whether the variable c 
contains a whitespace character (in this case, a space). If c is a whitespace 
character, the program prints the message "The character is a whitespace character." 
Otherwise, it prints the message "The character is not a whitespace character."

#include <stdio.h>

int main() {
    char c = ' ';
    if (c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f' || c == '\v') {
        printf("The character is a whitespace character.\n");
    } else {
        printf("The character is not a whitespace character.\n");
    }
    return 0;
}


#include <stdio.h>
#include <ctype.h>

int main() {
    char c = '.';
    if (ispunct(c)) {
        printf("The character is a punctuation character.\n");
    } else {
        printf("The character is not a punctuation character.\n");
    }
    return 0;
}

In this example, the ispunct() function is used to check whether the variable c 
contains a punctuation character (in this case, a period). If c is a punctuation 
character, the program prints the message "The character is a punctuation character.
" Otherwise, it prints the message "The character is not a punctuation character."

#include <stdio.h>

int main() {
    char c = '.';
    if (c == '.' || c == ',' || c == ';' || c == '?' || c == '!' || c == ':' || c == '-') {
        printf("The character is a punctuation character.\n");
    } else {
        printf("The character is not a punctuation character.\n");
    }
    return 0;
}