Program not detecting if statement

Question

So I was making a program that computes Pythagorean triples, as long as c is lower than the number entered by the user. So I used 3 while loops to accomplish this. What I also want to accomplish is print to the screen, the set of triples that has the thinnest interior angle, has to be a right-angled triangle. Basically, I calculated using the sine law the smallest angle for each of the triples, and then stored that smallest in an array, and right after it the three indexes of the array represent its corresponding triples. Then I made a method to compare each angle from the triples and if one was greater to store it in the initial four spots of the array. I am currently not worrying about the array size and have declared it as 9999. So the problem is that when I compare more than 1 set of triples, the program does not make the 1st set of indexes in the array equal to the triple with the smallest angle. I agree that the procedure that I have used is very inefficient and time consuming, but if you could give me some sort of solution or even guide me in the right direction I'd appreciate it. Thanks. Oh and here is my code,

#include <stdio.h>
#include <math.h>
#define PI 3.14159265

static int a[9999];

int main(void)
{

    int side1, side2, hyp, num;
    int i = 0;
    int j;
    side1 = 1;
    hyp = 0;

    printf("Please enter a number\n");
    scanf("%d", &num);

    while (side1 < num) {
    side2 = 1;

    while (side2 < num) {
        hyp = 1;

        while (hyp < num) {
        if (side1 * side1 + side2 * side2 == hyp * hyp && side1 < side2) {

            printf("The side lengths are %d,%d,%d\n", side1, side2, hyp);

            float angle1 = (asin((float) side1 / hyp) * (180 / PI));
            float angle2 = (asin((float) side2 / hyp) * (180 / PI));

            if (angle1 > angle2) {
            a[i] = (int)angle2;
            a[i + 1] = side1;
            a[i + 2] = side2;
            a[i + 3] = hyp;

            } else if (angle2 > angle1) {
            a[i] = (int)angle1;
            a[i + 1] = side1;
            a[i + 2] = side2;
            a[i + 3] = hyp;

            } else {
            a[i] = (int)angle1;
            a[i + 1] = side1;
            a[i + 2] = side2;
            a[i + 3] = hyp;
            }
            i=i+4;
        }
        hyp++;
        }
        side2++;
    }
    side1++;
    }
      a[i+1]=99.99;
      a[i+2]=99.99;
      a[i+3]=99.99;
      a[i+4]=99.99;

compare(i);

    return (0);
}

void compare(int i)
{
    int j;

    for(j=0;j<i;j=j+4)
    {
        if (a[0]>a[j+4])
        {
            a[0]=a[j+4];
            a[1]=a[j+5];
            a[2]=a[j+6];
            a[3]=a[j+7];

        }
//printf("%d\n",a[0]);
    }
  printf("The thinnest triangle is formed by (%d , %d , %d)", a[1], a[2], a[3]);

}

Oh one more thing, the reason I have made some indexes 99.9 is so that when the loop is checking and it is not the last triple, I do not want an error,since the loop will have nothing further to compare the previous triples to. Ok I changed it to one equal sign, but now the output is always 99,99,99.

Please note = is for variable declaration and == for comparison/conditions — Drixson Oseña
– Drixson Oseña, Commented Oct 22, 2013 at 0:01

Mark Plotnick · Accepted Answer · 2013-10-21 23:56:07Z

1

Perhaps the four statements starting with a[0]==a[j+4] should be using = instead of ==.

answered Oct 21, 2013 at 23:56

Mark Plotnick

10.4k1 gold badge27 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user2229592 Over a year ago

But then why does it give me (99,99,99)

Mark Plotnick Over a year ago

Where it prints out the three values corresponding to the thinnest triangle, please also print out the value of i. Maybe it's 0.

Farmer Joe · Accepted Answer · 2013-10-21 23:56:25Z

0

switch your assignments to single equal signs = instead of double ones ==.

void compare(int i)
{
    int j;

    for(j=0;j<i;j=j+4)
    {
        if (a[0]>a[j+4])
        {
            a[0] = a[j+4]; // <- here,
            a[1] = a[j+5]; // <- here,
            a[2] = a[j+6]; // <- here,
            a[3] = a[j+7]; // <- and here

        }
    //printf("%d\n",a[0]);
    }
    printf("The thinnest triangle is formed by (%d , %d , %d)", a[1], a[2], a[3]);

}

answered Oct 21, 2013 at 23:56

Farmer Joe

6,1001 gold badge33 silver badges41 bronze badges

2 Comments

user2229592 Over a year ago

I did, but then if I enter 10 for example, the output is (99,99,99)

Farmer Joe Over a year ago

You are assigning a[i+1]=99.99; etc. to an array of type int. The array will parse the floats into type int aka 99. I think a safer value for triangles could be 181 or something, since no 2D triangle has more than 180 degrees. If you print out your angles you will see this. I entered 10 into your code and received (99, 99, 99) with angle 0.

Collectives™ on Stack Overflow

Program not detecting if statement

2 Answers 2

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related