When writing c# timed lock screen software, the initial value of TextBox cannot be null, otherwise it will be abnormal

summer · Posted on 1/23/2019 9:19:06 AM

When debugging, the value of TextBox.text is not null, and there must be an initial value, which is mainly implemented through the two methods of TextBox: Get Focus Enter and Lose Focus: Leave.

The idea is as follows:

1. Set a string constant as the initial value of the TextBox;

2. In the interface construction method, assign the default value to the TextBox, and set the ForeColor of the TextBox to gray;

3. Write the Get Focus Method TextBox_Enter (object sender, EventArgs e) to determine whether the Text of the TextBox is equal to the default value.

Yes: Empty the TextBox content and change the foreground color ForeColor to the normal color

4. Lose focus method TextBox_Leave (object sender, EventArgs e) to determine whether the Text of the TextBox is empty, and if it is, it will display the default value in gray again

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[Communication] When writing c# timed lock screen software, the initial value of TextBox cannot be null, otherwise it will be abnormal

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