能否在运行时修改DDV_MinMaxInt的数值范围？

Let me break down everything you need to know about DDV_MinMaxInt—one of MFC's standard dialog data validation routines—along with how to set up DDX/DDV for your dialog controls.

What is DDV_MinMaxInt? #

DDV_MinMaxInt is a built-in MFC function designed to validate that an integer value from a dialog control falls within a specified range. It's part of the Dialog Data Validation (DDV) system, which works hand-in-hand with Dialog Data Exchange (DDX) to simplify reading/writing control values and validating user input.

Setting Up DDX/DDV with DDV_MinMaxInt #

The easiest way to set this up is using the Add Member Variable Wizard—no manual code writing required initially:

• Right-click on your target dialog control (e.g., an edit box for age input) and select Add Member Variable.
• In the wizard:
  • Set the Category to Value and Variable type to int (or another integer type like UINT).
  • Enter a descriptive variable name (e.g., m_nUserAge).
  • Switch to the Validation tab, check the Range box, then input your desired minimum and maximum values (e.g., 18 and 99 for adult age validation).
  • Click Finish—the wizard will auto-generate all necessary DDX and DDV code.

Example Generated Code #

Once you complete the wizard, your dialog's DoDataExchange method will include code like this:

void CMyDialog::DoDataExchange(CDataExchange* pDX)
{
    CDialogEx::DoDataExchange(pDX);
    // DDX handles exchanging data between the control and your variable
    DDX_Text(pDX, IDC_EDIT_USER_AGE, m_nUserAge);
    // DDV validates the variable is within the specified range
    DDV_MinMaxInt(pDX, m_nUserAge, 18, 99);
}

When the user tries to close the dialog, MFC automatically runs this validation. If m_nUserAge is outside 18-99, it'll pop up a default error message and prevent the dialog from closing until the input is corrected.

Important Tips #

• DDV_MinMaxInt only works with integer types. For floating-point values, use DDV_MinMaxFloat instead.
• If you want a custom error message instead of MFC's default, you can replace the auto-generated DDV call with your own validation logic (still leveraging DDX for data exchange).
• DDX/DDV saves you from writing repetitive code to read control values, parse them, and validate them manually—letting you focus on your app's core functionality.

内容的提问来源于stack exchange，提问作者Andrew Truckle