稍微混淆了一些C＃编码 [英] Slightly confused to some C# coding

问题描述

我的程序中有这部分代码

I have this part of the code in my program

int remainder = sum % 26;

     byte[] code = Encoding.ASCII.GetBytes(check);
     int chk = code[0];
     chk = chk - 65;                  // Subtract 65 from ASCII value for comparison i.e.
                                      // A = 0, B = 1, C = 2 onwards
     /* If we have check letter let say J its ascii value is 74 so chk will have value 9
        and as security number is 1122334455 sum = 165 and reminder = 9
      */
     if (remainder == chk)
     {

我的讲师帮助我写了那篇文章，但我不明白它的作用。我无法抓住他，我的截止日期是明天。我必须加上10个数字的总和，然后字母表的每个字母都分配了一个数字，所以A = 0，B = 1等等，我没有得到的是J = 74怎么样，为什么我必须-65？如果我从我的程序中取出chk = chk -65代码，那么它就不起作用了。有什么见解？

My lecturer helped me write that part, but I do not understand what it does. I can't get hold of him and my deadline is in for tomorrow. I have to add up the sum of 10 numbers and then each letter of the alphabet is assigned a number so A =0, B=1 etc etc, what i don't get is how does J = 74 and why do I have to -65? If i take the chk = chk -65 code out of my program then it does not work. Any insight?

推荐答案

您使用的映射（'A'< - > 0，'B'< - > 1 ，'C'< - > 2，... ）用于计算字符串上的校验和，但它通常在计算机上找不到，即ASCII [ ^ ]一个（'A'< - > 65，'B'< - > 66，'C'< - > 67，.. 。）。



幸运的是，两个'编码'（你的和 ASCII 一个）只有区别对于偏移，因此

The mapping you use ('A'<->0, 'B'<->1, 'C'<->2, ...) is handy for computing a checksum on a string but it is not the same usually found on computer, that is the ASCII[^] one ('A'<->65, 'B'<->66, 'C'<->67, ...).

Luckily the two 'encodings' (yours and the ASCII one) differ only for an offset, hence

char 你的 = char ASCII - 65

charyours = charASCII - 65

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