Exercise 04

Exercise 04: Checking if a Number is Negative

Your fourth task is to write a C function called my_isneg that displays either 'N' if the integer passed as a parameter is negative, or 'P' if it is positive or null.
However, there's a twist: you can only use the my_putchar function to output characters. The my_putchar function takes a single character as input and outputs it.

#include <unistd.h>

void my_putchar(char c)
{
    write(1, &c, 1);
}

Expected Output:

N (if the input is negative)
P (if the input is positive or zero)

Hints

Before diving into the solution, here are some hints to help you tackle the problem:

• Understand the basic conditional statements in C.
• Consider using an if-else statement to check the value of the integer.
• Use the provided my_putchar function to output the corresponding character.

These hints should give you a good starting point to work on the exercise. Good luck!

Solution

#include <unistd.h>

void my_putchar(char c)
{
    write(1, &c, 1);
}

/*
* This function, my_isneg, displays 'N' if the integer n
* is negative, or 'P' if it is positive or zero.
* It uses the my_putchar function to output characters.
*/
int my_isneg(int n) {
    if (n < 0) {
        my_putchar('N');
    } else {
        my_putchar('P');
    }

    // Return 0 to indicate successful execution
    return 0;
}

Explanation:

• In this solution, we use an if-else statement to check whether the integer n is negative.
• If n is less than 0, we output 'N' using the my_putchar function.
• Otherwise, we output 'P' using the my_putchar function.
• This ensures that the correct character is displayed based on the value of the integer n.

And voila, you've completed your fourth exercise in C programming !