[英]Checking textbox for valid input in a loop or try catch c#
I am having trouble validating user input, I have the following loop which definitely catches it but when the loop starts again the user doesn't have a chance to enter a different value so the value is the same and just creates an endless loop. 我无法验证用户输入,我有以下循环肯定会捕获它,但是当循环再次启动时,用户没有机会输入不同的值,因此值相同,只是创建一个无限循环。
private void guess_Click(object sender, EventArgs e)
{
int guessInt = 0;
bool pass = false;
int number;
while (pass == false)
{
if (guessInput.Text != "")
{
pass = Int32.TryParse(guessInput.Text, out number);
if (pass)
{
guessInt = number;
}
else
{
MessageBox.Show("You did not enter an integer, please enter a integer", "Invalid Values", MessageBoxButtons.OK, MessageBoxIcon.Error);
guessInput.Text = "";
}
}
else MessageBox.Show("You did not enter anything, please enter a integer", "Invalid Values", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
guess.Enabled = false;
next_Guess.Enabled = true;
if (guessInt == randomArray[x])
{
result.Text = ("You Win! The correct number was " + randomArray[x]);
right += 1;
correctAnswers.Text = right.ToString();
}
else
{
result.Text = ("Sorry you lose, the number is " + randomArray[x]);
wrong += 1;
incorrectAnswers.Text = wrong.ToString();
}
hintLabel.Enabled = false;
x++;
}
So how can the user have a chance to reenter a value and the loop start again or should I be using a try/catch attempt here? 那么用户如何有机会重新输入一个值并重新开始循环,或者我应该在这里使用try / catch尝试?
It seems you don't need a while there: 看来你在那里不需要一段时间:
int number;
if(guessInput.Text != "")
{
var pass = Int32.TryParse(guessInput.Text, out number);
if (pass)
{
guessInt = number;
}
else
{
MessageBox.Show("You did not enter an integer, please enter a integer", "Invalid Values", MessageBoxButtons.OK, MessageBoxIcon.Error);
guessInput.Text = "";
}
}
if you want to validate also for empty values, just remove the first if: 如果你想验证空值,只需删除第一个if:
int number;
var pass = Int32.TryParse(guessInput.Text, out number);
if (pass)
{
guessInt = number;
}
else {
MessageBox.Show("You did not enter an integer, please enter a integer", "Invalid Values", MessageBoxButtons.OK, MessageBoxIcon.Error);
guessInput.Text = "";
}
int number;
if(string.IsNullOrEmpty(guessInput.Text))
{
MessageBox.Show("You did not enter an integer, please enter a integer", "Invalid Values", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
if(Int32.TryParse(guessInput.Text, out number))
{
guessInt = number;
}else
{
MessageBox.Show("You did not enter an integer, please enter a integer", "Invalid Values", MessageBoxButtons.OK, MessageBoxIcon.Error);
guessInput.Text = "";
return;
}
// when come to here you have guessInt, process it
guess.Enabled = false;
next_Guess.Enabled = true;
if (guessInt == randomArray[x])
{
result.Text = ("You Win! The correct number was " + randomArray[x]);
right += 1;
correctAnswers.Text = right.ToString();
}
else
{
result.Text = ("Sorry you lose, the number is " + randomArray[x]);
wrong += 1;
incorrectAnswers.Text = wrong.ToString();
}
hintLabel.Enabled = false;
x++;
As soon as the user clicks OK on the messagebox, the loop is going to run again without giving the user a chance to change the value. 一旦用户在消息框上单击“确定”,循环将再次运行,而不会让用户有机会更改该值。
What you need to do is run validation only when they enter a guess. 您需要做的是仅在输入猜测时运行验证。 That is, rather than have a loop, have some code that is triggered by an event (such as clicking a button) or by the validation callback provided by winforms.
也就是说,不是有一个循环,而是有一些由事件(例如单击按钮)或winforms提供的验证回调触发的代码。
Here's an example and short article I found on using the validation callback: http://blog.scosby.com/post/2010/02/11/Validation-in-Windows-Forms.aspx 这是我在使用验证回调时发现的一个示例和简短文章: http : //blog.scosby.com/post/2010/02/11/Validation-in-Windows-Forms.aspx
In that example, see: 在该示例中,请参阅:
private void buttonSave_Click
- this is where you would put your messagebox, and private void buttonSave_Click
- 这是你放置消息框的地方,和
private void textBoxNumber_Validating
- this is where you would put your pass = Int32.TryParse(guessInput.Text, out number)...
code. private void textBoxNumber_Validating
- 这是你把pass = Int32.TryParse(guessInput.Text, out number)...
代码放到的地方。
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