C++ While Loop Break

Question

My goal is to create a C++ program that executes a chunk of code repeatedly until the user enters in an appropriate value and does so with the use of a while loop. My code is just repeating over and over and even if I input a "0" it still repeats the chunk of code in the loop.

Here is my source code:

#include <iostream>
using namespace std;

int main()
{
    int num = 0;
    bool repeat = true;
    while (repeat = true)
    {
        cout << "Please select an option." << endl;
        cout << "[1] Continue Program" << endl;
        cout << "[0] Terminate Program" << endl;
        cout << "---------------------" << endl;

        repeat = false;

        cin >> num;
        cout << endl;

        if (num = 1)
        {
            repeat = true;
            //execute program
        }
        else if (num = 0)
            repeat = false;
        else
            cout << "Please enter an appropriate value.";
    }

    return 0;

}

What did you notice, when stepping through your program line by line using a debugger? — πάντα ῥεῖ, Sep 25 '14 at 02:23

score 2 · Answer 1 · edited May 23 '17 at 11:57

2

  while (repeat = true)
                ^^

is one of your problems:

  while (repeat == true)
                ^^

With an assignment, the condition always evaluates to a true.

Some people advocate using Yoda condition to avoid these typos. Another way is to simply compile your program with the highest warning levels:

-Wall

edited May 23 '17 at 11:57

Community

1
1

answered Sep 25 '14 at 02:23

Alok Save

202,538
53
430
533

Switch all warnings on and listen to them? – πάντα ῥεῖ Sep 25 '14 at 02:26
@πάνταῥεῖ: Indeed or alternatively, play Yoda! ;-) – Alok Save Sep 25 '14 at 02:27
Aww, greenish color I spot in my face ;-) ... – πάντα ῥεῖ Sep 25 '14 at 02:29
2

Best answer, this is – M.M Sep 25 '14 at 02:34

score 2 · Answer 2 · answered Sep 25 '14 at 02:26

2

Check your operators. You're using the assignment operator = instead of the comparison operator == in your while and if arguments.

answered Sep 25 '14 at 02:26

cognoscente

88
1
8

score 1 · Accepted Answer · answered Sep 25 '14 at 02:23

1

while (repeat = true)

In the while condition, you are using the assignment operator =, not equality ==.

It's valid C++ syntax, but not what you expected. repeat is assigned to true, so the condition is always true.

The same error exists in if (num = 1) and else if (num = 0).

answered Sep 25 '14 at 02:23

Yu Hao

119,891
44
235
294

Switch all warnings on and listen to them? – πάντα ῥεῖ Sep 25 '14 at 02:25
This is the correct answer, and is more descriptive than the other. – Chantola Sep 25 '14 at 02:25
Thank you! I am pretty new to programming, so I appreciate the help! – Michael Barney Jr Sep 25 '14 at 02:28
@MichaelBarneyJr As πάντα ῥεῖ said, some compiler may give you a warning on this, check if your compiler is one of them. – Yu Hao Sep 25 '14 at 02:30

C++ While Loop Break

3 Answers3