Question

以下程序尝试加密字符串并保存到文本文件中，然后打开文件，解密并显示消息。

这是代码 -

private: System::Void saveToolStripMenuItem_Click(System::Object^  sender, System::EventArgs^  e) {
             SaveFileDialog^ dlg = gcnew SaveFileDialog();
             dlg->Filter = "Text Files|*.txt";
             char key = 'a';
             if(dlg->ShowDialog()==Windows::Forms::DialogResult::OK)
             {
                 String^ stream = txtOutput->Text;
                 char* num = new char[stream->Length];
                 char* xorchar = (char*)(void*)Marshal::StringToHGlobalAnsi(stream);
                 int i=0;
                 for(i=0;i<stream->Length;++i){
                     num[i] = *xorchar ^ key;
                     *xorchar++;
                 }

                 num[i] = '\0';  //add trailing NULL
                 //Marshal::FreeHGlobal((System::IntPtr)(void*)xorchar);  THIS WAS GIVING AN ERROR, NOT SURE WHY
                 String^ save = gcnew String(num);
                 System::IO::File::WriteAllText(dlg->FileName, save);
             }

         }
private: System::Void openToolStripMenuItem_Click(System::Object^  sender,      System::EventArgs^  e) {
         OpenFileDialog^ dlg = gcnew OpenFileDialog();
         dlg->Filter = "Text Files|*.txt";
         String^ stream;
         char key = 'a';
         if(dlg->ShowDialog()==Windows::Forms::DialogResult::OK)
         {
            stream = System::IO::File::ReadAllText(dlg->FileName);


            char* num = (char*)(void*)Marshal::StringToHGlobalAnsi(stream);
            int i=0;
            for (i=0;i<stream->Length;++i)
            {
                num[i] = num[i] ^ key;   //DECRYPT
            }

            String^ orig_stream = gcnew String(num);
            txtOutput->Text = orig_stream;

         }
     }

现在的问题是，当我输入一个字符串时，它只适用于不等于键的字符。例如，设键='a'

例如：INPUT：“我喜欢这个”//这将正确解密。

INPUT：“我喜欢苹果”//只有'我喜欢'会解密，休息不会出现。

即，如果遇到字符'key'（在本例中为'a'），它将停止解密。

感谢任何帮助。谢谢！

Answer 1

与自身xor'd的值将始终产生0. A 0 char也称为空终止符（0 == '\0'）。 C ++中的字符串是以空值终止的，也就是说它们在空终止符处停止。

简单示例：

#include <iostream>

int main(){
  char str[] = "hi there!\0this will not get printed.";
  std::cout << str;
}

Visual C ++ XOR加密错误

1 个答案: