My program doesn't end

Question

I'm new too c++ and I had to design a program that determines the first four triangular square numbers and the output is exactly how I want it to be, but it wont quit after its printed the first four. I can't figure out what it could be. I can't CTRL C because I will get points taken off. What is the issue here?

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    //Prints name line
    cout<<"*********** BY: ********"<<endl;

    //Initializing
    const int HOW_MANY=4;
    int num=1;
    int tsn=0;
    int z=1;
    int x=0;
    //How many TSN it will find and be printed
    while (x<=HOW_MANY)
    { 
        //
        int sum=0;
        for (int y=0;y<512;y++)
        {
                sum+=y;
                tsn=pow(num,2);
                //Tests if the numbers are TSN
                if ((sum==tsn) || (num+1)/sqrt(num)==sqrt(num))
                {

                    //Prints 1-HOW_MANY TSN and what they are
                    cout<<"Square Triangular Number "<< z <<" is: "<< tsn <<endl;
                    z++;
                    x++;
                }
        }
        num++;
    }
    return 0;
}

Answer 1

x begins at 0 . Every time you find and print a number it gets incremented. You'll continue this, so long as x<=HOW_MANY .

You say your program finds 4 numbers but keeps running. After 4 hits, x will be 4. Is 4 <= 4 ? The answer is yes, so your program keeps running.

Either change the condition to x < HOW_MANY , or initialize x to 1 .

---

EDIT

Did a little leg work, it turns out the sum of all the numbers in the range [1,512] is 131328 . The 5th square triangle number is 1413721 .

This means after you find the fourth triangle number, you will never sum high enough to find the next one. This will result in the infinite loop you're seeing.

The answer above is still the correct fix, but this is the reason you end up with an infinite loop.

Answer 2

如果x = 0则需要写while (x<HOW_MANY)而不是while (x<=HOW_MANY) while (x<HOW_MANY) 。

Answer 3

for should be used for iteration and while should be used for condition testing.

The problem, as has been noted, is that your x condition variable is never being incremented to get you out of the outer loop. That's a logic error that can be avoided by using the appropriate control structure for the job.