PHP凯撒密码 [英] PHP Caesar cipher

问题描述

（jsfiddle例子在这里：）

我正在制作凯撒密码 - 基本上这是一个字母转换，移位参数为3如下：
a => d，b => e，c => f，...

到目前为止，我的代码是

  $ string =hello; 
回显< p> 。 $字符串。 < / P> 中; 
 $ newstring =hello; （$ i = 0; $ i< strlen（$ string）; $ i ++）{
 
 $ ascii = ord（$ string [$ i]）; 
 
; 
 if（$ ascii == 90）{//大写字母绑定
 $ ascii = 65; //重置为'A'
} 
 else if（$ ascii == 122）{//小写绑定
 $ ascii = 97; //重置为'a'
} 
 else {
 $ ascii ++; 
} 
 $ newstring [$ i] = chr（$ ascii）; 
 
} 
 
 echo< p> 。 $ newstring。 < / P> 中; 
  

并且它可以正常工作。

I如下所示：

 < form> 
< table> 
< tr>< th class =w>消息：< / th> 
< td>< textarea class =tonfocus ='this.select（）'name = msg> HELLO< / textarea>< / td> 
< / tr> 
< tr>第> Shift参数：< / th> 
< td>< input type = text size = 2 name = sp value ='11'>< / td> 
< / tr> 
< tr>< td>< / td>< td>< input type = submit name = submit value ='Encode'> 
< input type = submit name = submit value ='Decode'> 
< input type = button value ='清除'onclick ='this.form.elements.msg.value ='< / td>< / tr> 
< / table> 
< / form> 
  

我只需要更改PHP来输出表格，但不太清楚。所以，在textarea中，用户可以输入TESTING，选择一个8的移位参数，然后点击Encode，这将运行一个编码功能;同样，解码将运行解码功能。

任何想法如何更改PHP代码以使其按我喜欢的方式工作？

解决方案

首先，更改

  $ string = 你好; 
  

至

  $ string = $ _POST ['msg']; 
  

和

  $ newstring =hello; 
  

至

  $ newstring = $ string; 
  

然后，读取shift参数的值：

  $ sp = $ _POST ['sp'] 
  

现在，而不是做

  $ ascii ++; 
  

通过shift参数的值增加其值。如果$ sp的值是8，那么最终的$ ascii值将是$ ascii + 8

或者您可以执行elclanrs建议的操作：$ char ='一个'; ++ $字符; // =>b。但不是++ $ char; do $ char + = $ sp;

在增加$ ascii的值的同时，您必须检查边界。可以使用循环并将$ ascii的值增加1。

因此在for循环中：

<$ （$ i = 0; $ i< strlen（$ string）; $ i ++）{...}
p>



会有另一个for循环，并且所有的边界条件都会进入循环。例如：

$ p $ for（$ i = 0; $ i< strlen（$ string）; $ i ++）{

$ ascii = ord（$ string [$ i]）;
for（$ j = 0; $ j <$ sp; $ j ++）{
if（$ ascii == 90）{//大写限制
$ ascii = 65; //重置为'A'
}
else if（$ ascii == 122）{//小写绑定
$ ascii = 97; //重置为'a'
}
else {
$ ascii ++;
}
}
$ newstring [$ i] = chr（$ ascii）;






（我不是PHP开发人员，所以语法可能是错的。）




(jsfiddle example here: caesar cipher)

I am making a Caesar cipher - it's an alphabetic shift, basically; a shift parameter of 3 is as follows: a => d, b => e, c => f, ...

My code so far is

$string = "hello";
echo "<p>" . $string . "</p>";
$newstring = "hello";

for ($i=0;$i<strlen($string);$i++) {

    $ascii = ord($string[$i]);
    if($ascii == 90) { //uppercase bound
        $ascii = 65; //reset back to 'A' 
        } 
    else if($ascii == 122) { //lowercase bound
        $ascii = 97; //reset back to 'a' 
        } 
    else {
        $ascii++;
    }
    $newstring[$i] = chr($ascii);

}

echo "<p>" . $newstring . "</p>";

and it works okay.

I would like a user to be able to enter their own string into a form's textarea as follows:

<form>
    <table>
        <tr><th class="w">Message:</th>
            <td><textarea class="t" onfocus='this.select()' name=msg>HELLO</textarea></td>
        </tr>
        <tr><th>Shift Parameter:</th>
            <td><input type=text size=2 name=sp value='11'></td>
        </tr>
        <tr><td></td><td><input type=submit name=submit value='Encode'>
        <input type=submit name=submit value='Decode'>
        <input type=button value='Clear' onclick='this.form.elements.msg.value=""'</td></tr>
    </table>
</form>

I just need to change the PHP to output the table, but don't quite know how. So, in textarea, a user could type "TESTING", choose a shift parameter of 8, and click "Encode" and that would run an encode function; likewise, "Decode" would run a decode function.

Any ideas how to change the PHP code to make it work the way I'd like?

解决方案

First,change

$string = "hello";

to

$string = $_POST['msg'];

and

$newstring = "hello";

to

$newstring = $string;

Then, read the value of shift parameter:

$sp = $_POST['sp']

Now, instead of doing

$ascii++;

increment its value by the value of shift parameter. if the value of $sp is 8, the final $ascii value would be $ascii + 8

Or you can do what "elclanrs" has suggested : $char = 'a'; ++$char; //=> "b". But instead of ++$char; do $char+=$sp;

While incrementing the value of $ascii, you must check for the bounds. May be use a loop and increment the value of $ascii by 1.

So Inside your for loop:

for ($i=0;$i<strlen($string);$i++) {...}

there will be another for loop and all the conditions for the bound would go inside it. Something like :

for ($i=0;$i<strlen($string);$i++) {

  $ascii = ord($string[$i]);
  for($j=0;$j<$sp;$j++){
    if($ascii == 90) { //uppercase bound
      $ascii = 65; //reset back to 'A' 
    } 
    else if($ascii == 122) { //lowercase bound
      $ascii = 97; //reset back to 'a' 
    } 
    else {
      $ascii++;
    }
  }
  $newstring[$i] = chr($ascii);

}

(I'm not a PHP developer, so the syntax might be wrong.)

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