Secondary development of WinForm controls

One, the input field is not empty verification

    ① First of all, create a class library, and then add an additional component class

in it

    ②Add a reference to the control namespace in the class library (System.Windows.Forms)

3 Change the base class to the control that needs to be inherited (such as TextBox)

public partial class SuperTextBox : TextBox

    ④ Drag and drop errorProvider

in the editing area

  ⑤ Write a warning method and associate an error message

public bool CheckEmpty(){if(this.Text==""){this.errorProvider.SetError(this,"cannot be empty"); //Subordinate component, reminding contentreturn true}else{this.errorProvider.SetError(this,empty);return false;}}

⑥ ⑥It can be applied directly in the project by the method of ordinary controls

    also must be called CheckEmpty(); in the function body for it to take effect.

Second, use regular expressions to achieve complex verification

Based on the above project, rewrite the verification method

public bool BeginCheckData(string regularExpress, string errorMsg){if(CheckEmpty() == false)return false;Regex objRegex = new Regex(regularExpress,RegexOptions.IgnoreCase); //Ignore caseif(!objRegex.IsMatch(this.Text)){this.errorProvider.SetError(this, "verification failed");return true}else{this.errorProvider.SetError(this,empty);return false;}}

Three, other programs call custom controls

Move the .dll code generated by the control scheme to the project that needs to be called, and then reference it in the toolbox