[Solved] Every time I start the project always just writes that ” THIS IS NOT VALID” even if the numbers that I give are right [closed]

by


  1. You are casting (bool) valid_triangel the address of the function instead of calling it. This will always be non-NULL and the corresponding true branch of the if condition will be executed irregardless of input.

  2. (non-issue) I don’t have cs50.h installed so I wrote a quick get_double() to test your code.

  3. Removed the declaration of valid_tringel() inside main().

  4. Fixed typo (triangle).

  5. (x + y >= z ) || (x + z >= y) || (z + y >= x ) is inverted in valid_triangle(). As you return boolean just express is directly instead of an if condition:

According to the first triangle inequality theorem, the lengths of any two sides of a triangle must add up to more than the length of the third side.1

  1. Used early return style in main() so the normal case is not indented (purely a matter of style).
#include <stdio.h>
#include <stdbool.h>

double get_double(const char *s) {
    printf("%s", s);
    double d;
    scanf("%lf", &d);
    return d;
}

bool valid_triangle(double x, double y, double z) {
    return
        x > 0 &&
        y > 0 &&
        z > 0 &&
        x + y > z &&
        x + z > y &&
        z + y > x;
}

int main(void) {
    double a = get_double("give me first length : ");
    double b = get_double("give me second length : ");
    double c = get_double("give me third length : ");
    if(!valid_triangle(a, b, c)) {
        printf("THIS IS NOT VALID\n");
        return 0;
    }
    printf("THAT IS A TRIANGLE\n");
}

and here is example output:

give me first length : -1
give me second length : 1
give me third length : 10
THIS IS NOT VALID

give me first length : 1
give me second length : 2
give me third length : 3
THIS IS NOT VALID

give me first length : 7
give me second length : 10
give me third length : 5
THAT IS A TRIANGLE

solved Every time I start the project always just writes that ” THIS IS NOT VALID” even if the numbers that I give are right [closed]