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Question

我已经编写了一组函数来验证表单中的文本框是否满足它们所需的字段需求，如下所示

私有空ValidateForm()

        {
        //Initialise the variables for validation check and call the related functions
        bool bisValidhost = ValidateHost();
        bool bisValidPassword = ValidatePassword();
        bool bisUsername = ValidateUsername();

        //If any of the entries is missing then show error message
        if(bisValidhost && bisValidPassword && bisUsername == false)
            {
            MessageBox.Show("This is not a Valid Entry!");                
            }         
        }


    /// <summary>
    /// This function validate the Required field need of txtHost.
    /// </summary>
    /// <returns></returns>
    private bool ValidateHost()
        {
        ErrorProvider errorProvider = new ErrorProvider();
        bool isValid = true;

        //If the txtHost is empty, show a message to user
        if(txtHost.Text == string.Empty)
            {
            errorProvider.SetError(txtHost, "Please enter the host address");
            isValid = false;
            }
        else
            errorProvider.SetError(txtHost, string.Empty);
        return isValid;
        }


    ///<summary>
    /// This function validate the Required field need of txtUsername.
    /// </summary>
    /// <returns></returns>
    /// </summary>
    /// <returns></returns>
    private bool ValidateUsername()
        {
        ErrorProvider errorProvider = new ErrorProvider();
        bool isValid = true;

        //If the txtUsername is empty, show a message to user
        if(txtUsername.Text == string.Empty)
            {
            errorProvider.SetError(txtUsername, "Please enter the Username");
            isValid = false;
            }
        else
            errorProvider.SetError(txtUsername, string.Empty);
        return isValid;
        }


    ///<summary>
    /// This function validate the Required field need of txtPassword.
    /// </summary>
    /// <returns></returns>
    /// </summary>
    /// <returns></returns>
    private bool ValidatePassword()
        {
        ErrorProvider errorProvider = new ErrorProvider();
        bool isValid = true;

        //If the txtPassword is empty, show a message to user
        if(txtPassword.Text == string.Empty)
            {
            errorProvider.SetError(txtPassword, "Please enter the Password");
            isValid = false;
            }
        else
            errorProvider.SetError(txtPassword, string.Empty);
        return isValid;
        }

但是它没有显示正确的消息。

Answer 1

我可能误解了你的IF结构

if(bisValidhost && bisValidPassword && bisUsername == false) 

但我觉得你想

if( ! ( bisValidhost && bisValidPassword && bisUsername ))

假设你的答案都是真的(即:有效)，那么它就会解释为

if ( TRUE and TRUE and ( TRUE == FALSE ))

如果前两个选项中有一个是假的，而最后一个是ok的，那么您应该

IF ( FALSE AND FALSE AND ( TRUE == FALSE))

通过执行逻辑NOT (!)检查它们中是否有任何一个失败是您想要的。

如果不是(3个部分都有效)