Question

我是编程新手，我正在学习C＃。我正在开发一个程序来加密和解密在文本框中输入的文本。

当用户点击按钮加密或解密文本时，我想确保文本和密码文本框不为空。所以，我正在使用逻辑条件运算符&&和!=来评估文本框，然后运行加密文本的代码。当我将文本框的text属性的值与空字符串进行比较时，我似乎得到了错误的结果。

当我单击加密或解密按钮而文本框中没有任何数据时，语句：if (text != " " && encryptPassword != " ")的行为就好像每个测试都为真，并且无论如何都要运行加密或解密代码。我已尝试使用equals，使用括号，并将顺序撤销无效。请帮忙。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace CryptoMakerII
{
    public partial class CryptoMakerII : Form
    {

        public CryptoMakerII()
        {
            InitializeComponent();

        }

        private void UpdateControls(string crypto)
        {
            if (crypto == "Encrypt")
            {
                lblEncryptPassword.Visible = false;
                txtEncryptPassword.Visible = false;
                btnEncrypt.Visible = false;
                txtDecryptPassword.Visible = true;
                btnDecrypt.Visible = true;
                lblDecryptPassword.Visible = true;
                lblText.Text = "Encrypted Text";

                //txtDecryptPassword.Text = " ";

                //txtEncryptPassword.Text = " ";

            }
            else
            {

                lblEncryptPassword.Visible = true;
                txtEncryptPassword.Visible = true;
                btnEncrypt.Visible = true;
                txtDecryptPassword.Visible = false;
                btnDecrypt.Visible = false;
                lblDecryptPassword.Visible = false;
                lblText.Text = "Text to Encrypt";
                txtDecryptPassword.Text = " ";
                txtEncryptPassword.Text = " ";





            }
        }
        private void btnEncrypt_Click(object sender, EventArgs e)
        {
            DES_Crypto desCrypto = new DES_Crypto();
            string text = txtText.Text;
            string encryptPassword = txtEncryptPassword.Text;

            if (text != " " && encryptPassword != " ")
            {
                string encryptedText = desCrypto.EncryptString(text, encryptPassword);
                txtText.Text = encryptedText;
                UpdateControls("Encrypt"); 

            }
            else

            {
                MessageBox.Show("Please enter text to encrypt and password");
            }

        }



        private void btnDecrypt_Click(object sender, EventArgs e)
        {
            DES_Crypto desCrypto = new DES_Crypto();
            if (txtText.Text != " " && txtDecryptPassword.Text != " ")

                if (txtDecryptPassword.Text == txtEncryptPassword.Text)
                     {
                        string decryptedText = desCrypto.DecryptString(txtText.Text, txtDecryptPassword.Text);
                        txtText.Text = decryptedText;
                        UpdateControls("Decrypt");
                     }
                else
                {
                    MessageBox.Show("The password is incorrect!");
                }               
                else
                MessageBox.Show("Please enter password to decrypt");
        }
   }

}

Answer 1

您正在检查字符串是否完全等于1个空格字符，而不是检查它是否为空。 C＃有一个内置方法来检查字符串是否为空：

pthread_mutex_lock

所以而不是

pthread_mutex_lock

尝试

string.IsNullOrEmpty(str)

为什么If语句使用逻辑条件运算符＆amp;＆amp;和！=给我错误的结果？

1 个答案: