CODEWITHSUNDEEP
c
Vestrius
Vestrius

Reputation: 1

How to fix "Is Positive or Negative" C script?

#include <unistd.h>
#include <stdlib.h>

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

void    func_putchar(char c);

void    func_is_negative(char *n){
    if (n >= 0)
    {
        func_putchar('P');
    }
    else
    {
        func_putchar('N');
    }
}

int main ( int argc, char *argv[] ){
    char n = atoi (argv[1]);
    func_is_negative(&n);
}

I tried inserting a number through terminal, however each time I get a random result, it's either positive or negative. I think the code doesn't check the number submitted or translates it badly with atoi()

Upvotes: -1

Views: 188

Answers (2)

Baptiste
Baptiste

Reputation: 36

You do stange things in my point of view, Why char n = atoi(argv[1]), better use int n = atoi(argv[1]) because atoi return a int or a long.

After, I don't think that you need a pointer of n , func_is_negative(n); looks better for your case.

so replace the prototype of your functions too, void func_is_negative(int n) looks better cause you are using integers.

If I don't say mess, when you do : if (n >= 0) whith char *n, you are comparing a pointer (char *) whith 0 and the value of a pointer can't be 0 or less

Upvotes: 2

Asteroids With Wings
Asteroids With Wings

Reputation: 17454

You're checking whether the pointer to the char is greater than or equal to 0. After sign conversion, this may or may not be the case at any given time.

Check *n, not n. Or don't pass a pointer in in the first place (there's no need to).

You may also wish to consider using int rather than char, as your input is quite constrained at the moment and prone to overflows.

Upvotes: 1

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