我的任务是编写一个程序来读取标准输入，存储文本直到遇到 EOF，然后使用 Caesar block 密码加密文本。

解决方案的步骤:

1. 因此:将您的消息读入一个大缓冲区或一个字符串对象中。
2. 是否删除空格和标点符号
3. 然后计算消息中的字符数。
4. 选择第一个大于消息长度的完美正方形，分配一个该大小的 char 数组。
5. 将消息读入正方形该大小的数组从左到右，从上到下。
6. 从上到下、从左到右写下消息，您就已经加密了。

这是我目前所拥有的...它编译但不执行任何操作。我知道我一定错过了什么。任何帮助将不胜感激。

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
sử dụng không gian tên std;

int chính()
{
    // read in char from keyboard
    string buff;
    LÀM
    {
        cin >> buff;
    } while ( ! cin.eof()) ;

    // delete spaces and punctuation
    for ( int i = 0 ; i < sizeof ( buff ) ; i++ )
    {
        if ( !isalnum ( buff[i] ) )
        {
            buff.erase( i,1 );
            --i;
        }
    }

    // get length of edited string
    int static SIZE = buff.length(); //strlen (buff);

    // pick first perfect _square_ greater then the message length (ex:7x7)
    int squared = static_cast  ( sqrt( static_cast  ( SIZE )) + .5f );

    // allocate an array of char that size
    char ** board;
    board = new char *[squared]; // array of 'squared' char pointers
    for ( int i = 0 ; i < squared ; i++ )
        board[i] = new char[squared];

    // read messsage into a square array of that size from left to right top to bottom
    for ( int c = 0 ; c < squared ; c++ )
        for ( int r = 0 ; r < squared ; r++ )
            buff[r] = board[r][c];

    // write the message out top to bottom, left to right and its been encyphered
    for ( int r = 0 ; r < squared ; r++ )
        for ( int c = 0 ; c < squared ; c++ )
            cout << board[r][c] << endl;

    // delete array
    delete [] board;
    for ( int i = 0 ; i < squared ; ++i )
        delete [] board[i] ;

} // end main

câu trả lời hay nhất

我尝试编译并运行您的代码 - 发现了一些问题。

1) 您的“删除”循环进入无限循环。从数组的开头开始，遍历所有元素，在遍历时删除元素，并期望最后一切正常，这通常是非常糟糕的做法。从最后开始并向后工作要安全得多:

for(ii = buff.length() - 1; ii>=0; ii--) {
  if ( !isalnum ( buff[i] ) )
    {
    cout << "erasing " << buff[i] << endl;
    buff.erase( i,1 );
    }
  }
}

你会

delete [] board;

在删除数组中的单个元素之前...不确定语法是什么，但它看起来不对!

你的板子不够大。你必须使用 ceil 函数来确保你真的得到了“下一个最大”的数字:

square = ceil(sqrt(buff.length()));

还有一个大问题:您将(空)缓冲区复制到您的输入字符串中，而不是相反:

buff[r] = board[r][c];

应该是什么

ii = 0;
for(( int c = 0 ; c < squared ; c++ )
  for ( int r = 0 ; r < squared ; r++ )
    board[r][c] = buff[ii++];

可能还有其他人......仍在解决问题。

编辑:这是完整的工作代码。

    // read in char from keyboard
    int tôi;
    string buff;
    cout << "enter the text to be encoded" << endl;
    getline(cin,buff);
    cout << "done reading in the text!" << endl;
    cout << "buffer size is " << buff.length() << endl;
    cout << "the string is " << endl << buff << endl;
    // delete spaces and punctuation
    for ( i = buff.length()-1 ; i >=0 ; i--)
        {
            if ( !isalnum ( buff[i] ) )
           {
           buff.erase( i,1 );
            }
        }

// get length of edited string
 int static SIZE = buff.length(); //strlen (buff);
cout << "the string length is " << SIZE << endl;

 // pick first perfect _square_ greater then the message length (ex:7x7)
int squared = static_cast  ( ceil(sqrt( static_cast  ( SIZE ))));
cout << "size of board is " << squared << endl;
// allocate an array of char that size
char ** board;
board = new char *[squared]; // array of 'squared' char pointers
for ( i = 0 ; i < squared ; i++ )
    board[i] = new char[squared];

// read messsage into a square array of that size from left to right top to bottom
i = 0;
for ( int c = 0 ; c < squared ; c++ )
    for ( int r = 0 ; r < squared ; r++ )
       board[r][c] = toupper(buff[i++]);

  // write the message out top to bottom, left to right and its been encyphered
 for ( int r = 0 ; r < squared ; r++ ){
    for ( int c = 0 ; c < squared ; c++ ){
        cout << board[r][c];}
    cout << endl;
    }

   // delete array
    for ( i = 0 ; i < squared ; ++i )
     delete [] board[i] ;

    delete [] board;
} // end main

注意我改变了输入法来得到一个完整的句子，而不是一个单词；我将所有字符转换为大写(非常罗马 - 这意味着在句子开头、名称等处没有关于字符的提示)，仅在完整输出行(而不是每一行)的末尾添加回车符，以及之前发现的问题。

加密快乐!哦 - 一个事后的想法。一旦您确认一切看起来不错(通过阅读列中的文本很容易做到)，您将希望摆脱输出中的回车符。它当然应该显示为没有这些中断的单行文本!

关于c++ - block 密码，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15867988/