Print to stdout without `printf`, `puts`, `putchar`, etc

Please, how can I make my main() function print out the inputs, by calling a function named _putchar()?

We are not allowed to use built-in functions like printf(), puts(), putchar(), etc.

The instructions are as follows:

> - You are not allowed to use the standard library. Any use of functions like printf, puts, etc… is forbidden
>
> - You are allowed to use _putchar

Apparently, we are only allowed to create our own function, which can then be called to our main output.

Here is my code below:

#include <stdio.h>

int _putchar(char c)
{
    return 0;
}

int main()
{
    _putchar('_');
    _putchar('p');
    _putchar('u');
    _putchar('t');
    _putchar('c');
    _putchar('c');
    _putchar('h');
    _putchar('a');
    _putchar('r');
    _putchar('\n');
    return(0);
}

Expected output is:

> _putchar

You might be expected to implement _putchar using a system call such as write on POSIX systems or something similar on other platforms:

#include <unistd.h>

int _putchar(char c)
{
    return write(1, &c, 1) == 1 ? c : -1;
}

Here is my answer:

#include <stdio.h>

int _putchar(char c)
{
    int n = 0;
    n = write(1,&c,1);
    return n;
}

int main()
{
    int m = 0;
    m = _putchar('_');
    m = _putchar('p');
    m = _putchar('u');
    m = _putchar('t');
    m = _putchar('c');
    m = _putchar('c');
    m = _putchar('h');
    m = _putchar('a');
    m = _putchar('r');
    m = _putchar('\n');
    return(0);
}