文本框最大/最小数值C＃

Question

I want to create an if Statement that validates whether an input number in a textbox is between 0 to 100. For example:

NumericUpDown num = new NumericUpDown();

num.Maximum = 100;
num.Minimum = 0;

if (int.Parse(txtMid.Text) < num.Minimum && int.Parse(txtMid.Text) > num.Maximum)
{
    MessageBox.Show("Please input 0 to 100 only.");
}

That's all. Thanks in advance.

Answer 1

You need to parse the txtbox1.Text string into an integer:

int val = 0;
bool res = Int32.TryParse(txtbox1.Text, out val);
if(res == true && val > -1 && val < 101)
{
    // add record
}
else
{
    MessageBox.Show("Please input 0 to 100 only.");
    return;
}

Also, do you need to test one or two textboxes? If it's only one and you need the interval 0, 100, then your condition is wrong, because it always returns false (a number cannot be at the same time <= -1 and >= 101).

VERY IMPORTANT : I have reversed your if/else: you have to print the error in the else and add the record in the if.

Answer 2

First convert the text into Int then you can compare it. But be careful the entered text might not be the number for example user can enter abc instead of 12

You can use Int.TryParse(String) method to check whether the textbox contains valid number or not. If the number is valid then apply the if condition below

if(Convert.ToInt32(txtbox1.Text) <= -1 && Convert.ToIn32(textbox2.Text >= 101)
{

}

Answer 3

其他答案回答了您的直接问题，但输入数字的更好选择是使用NumericUpDown控件将输入限制为数字，并提供旋转控件。

Answer 4

Essentially what you want to do is the following:

• Get the current text from the textbox.
• Convert the text to a number (using the TryParse method for the type).
• If the text could not be converted to a number, notify the user and restore the text box to the last known good value (or an empty string, if no such value present) . If you don't do this you will leave the text box in an invalid state, which is probably not what you want.
• If the text could be converted, check that it is within the given range. If it is, store it as the last known good value for later use. If not, notify the user and restore the text box to the last known good value.

Answer 5

TextBox.Text property will return value as a string. So, first you have to parse the that string into integer. You can use following code :

int num = -2;
bool conversionSuccessful = int.tryParse(txtbox1.Text, out num);
if(conversionSuccessful) {
    if (num <= -1 && num >= 101) {
        MessageBox.Show("Please input 0 to 100 only.");
    return;
    }
}

You can find more information about conversion here and here

Answer 6

int val1=0,val2=0
try
{
val1 = Convert.ToInt32(txtbox1.Text);
val2 = Convert.ToIn32(textbox2.Text); 
}
catch
{
MessageBox.Show("Invalid Input");
}

// Do all the Checking here....