循环10次添加输入，在C＃中使用for和do while循环？

Question

I'm new taking a basic C# course and I'm having trouble getting an assignment to work. I built a basic calculator and it works fine. Now I had to add a new button called "Sum" that will take an input from one of my boxes (number1Txtbox) and add it to itself 10 times through a loop.

I poured through pages of my c# book and can't figure this one out. I figured out how to initialize the loop with the counter etc, I just can't get this to work for the life of me.

I was told to use a for loop, then switch to a do while loop. Which doesn't really make sense to me, I assumed I could do this with just a for loop. So my question is:

1) Do I even need to switch to a do while loop to do this?
2) What am I doing wrong?

Here is what I have so far and it just makes my program freeze when I attempt to hit the sum button after putting a number in the textbox:

private void sumBtn_Click(object sender, EventArgs e)
{
    int counter;
    int loopAnswer;
    int number1;

    number1 = int.Parse(number1Txtbox.Text);

    for (counter = 1; counter <= 10; counter++)
    {
        loopAnswer = number1 + number1;
        do
        {
            loopAnswer = loopAnswer + number1;
        } while (counter <= 10);

        equalsBox.Text = loopAnswer.ToString();
    }
}

Thanks guys!

Answer 1

You mixing things. You either do this:

private void sumBtn_Click(object sender, EventArgs e)
{
    int counter;
    int loopAnswer = 0;
    int number1 = int.Parse(number1Txtbox.Text);

    for (counter = 1; counter <= 10; counter++)
    {
        loopAnswer += number1; //same as loopAnswer = loopAnswer + number1;
    }
    equalsBox.Text = loopAnswer.ToString();
}

or this:

private void sumBtn_Click(object sender, EventArgs e)
{
    int counter = 1;
    int loopAnswer = 0;
    int number1 = int.Parse(number1Txtbox.Text);

    do
    {
        loopAnswer += number1; //same as loopAnswer = loopAnswer + number1;
        counter++;
    } while (counter <= 10);


    equalsBox.Text = loopAnswer.ToString();

}

Also, the final answer ( equalsBox.Text = loopAnswer.ToString(); ) should be out of the loop.

Answer 2

It freezes because when it enters the do while loop, the counter is never changed. If it's never changed, counter <= 10 is always true so you get an infinite loop. It is stuck there.

private void sumBtn_Click(object sender, EventArgs e)
{
    //these should default to 0, but we should to it explicitly, just in case.
    int loopAnswer = 0;
    int number1;

    if(int.TryParse(number1Txtbox.Text, out number1)
    {
        for (counter = 1; counter <= 10; counter++)
        {
            loopAnswer += number1;
        }

        equalsBox.Text = loopAnswer.ToString();
    }
    else
        equalsBox.Text = "Not A Number";
}

The TryParse here is just good practice. It takes care of a situation where you would have text input. A try catch block could also be used.

Answer 3

private void sumBtn_Click(object sender, EventArgs e)
{
    int counter;
    int loopAnswer = 0;
    int number1;

    number1 = int.Parse(number1Txtbox.Text);


    for (counter = 1; counter <= 10; counter++)
    {
            loopAnswer += number1;
    }


equalsBox.Text = loopAnswer.ToString();

}

Answer 4

Your program freezes because

        do
        {
            loopAnswer = loopAnswer + number1;
        } while (counter <= 10);

Doesn't update the counter variable at all. Therefore counter is never going to reach 10 so this loop is never going to exit.

to sum in a while loop do this

counter = 1;
do {
    loopAnswer += number1;
    counter++;
} while(counter <= 10);

Answer 5

Your inner loop (while) is running endlessly because counter is never increased, that's why your program hangs. Set a breakpoint on a line to be able to debug your program and gain a better understanding of how loops work.

To solve this assignment you only need one loop, definitly not nested loops. It doesnt matter what kind of looping mechanism you use.

Answer 6

This code cause an infinite loop (that is the reason of the freeze):

for (counter = 1; counter <= 10; counter++)
{
    loopAnswer = number1 + number1;
    do
    {
        loopAnswer = loopAnswer + number1;
    } while (counter <= 10);

    equalsBox.Text = loopAnswer.ToString();
}

Infact here you're looping from 1 to 10, and for each iteration you perform loopAnswer = loopAnswer + number1; until the condition counter <= 10 becomes false. But that never happens since in your do-while the counter variable doesn't change and so the program remains forever in the first iteration.

I think you should get rid of the inner do-while and put equalsBox.Text = loopAnswer.ToString(); outside the for-loop.

Answer 7

For the sake of examples, let's say that number1 = 4. When you execute the line loopAnswer = number1 + number1; the resulting value of loopAnswer will always be 8. If you wanted loopAnswer to increment, then you should use loopAnswer = loopAnswer + number1; , or the shorthand syntax loopAnswer += number1;

Regarding the use of a for loop versus a do-while , I'm guessing that it's not a matter of using both loops at the same time, it's a matter of using a for loop to illustrate the concept and then switching to use a do-while loop to illustrate the concept.

You could complete this exercise using a for loop like this:

for (counter = 1; counter <= 10; counter++)  
{  
    loopAnswer += number1; 
}

equalsBox.Text = loopAnswer.ToString();  

You could also accomplish the same functionality using a do-while loop like this:

int counter = 1;
do  
{  
    loopAnswer += number1;  
    counter++;
} while (counter <= 10);  

equalsBox.Text = loopAnswer.ToString();