请帮我解释一下函数
我的任务是记录一个没有注释的应用程序。但是，我一直无法理解以下功能。
private uint GetVersionHash(int encver, int realver)
{
int EncryptedVersionNumber = encver;
int VersionNumber = realver;
int VersionHash = 0;
int DecryptedVersionNumber = 0;
string VersionNumberStr;
int a = 0, b = 0, c = 0, d = 0, l = 0;
VersionNumberStr = VersionNumber.ToString();
l = VersionNumberStr.Length;
// I am specifically struggling with the purpose and intent of this loop.
for (int i = 0; i < l; i++)
{
VersionHash = (32 * VersionHash) + (int)VersionNumberStr[i] + ;
}
a = (VersionHash >> 24) & 0xFF;
b = (VersionHash >> 16) & 0xFF;
c = (VersionHash >> 8) & 0xFF;
d = VersionHash & 0xFF;
DecryptedVersionNumber = (0xff ^ a ^ b ^ c ^ d);
if (EncryptedVersionNumber == DecryptedVersionNumber)
{
return Convert.ToUInt32(VersionHash);
}
else
{
return 0;
}
}
根据我目前的理解，它右移 5 并增加了一些价值。
还有一些进一步的信息：
encver似乎是一个加密版本，作为 int （它是从文件中读取的）realver似乎是我们正在测试匹配的版本。它在另一个函数中循环到此函数，从short.MinValue到short.MaxValue
此循环的目的是什么？代码是如何达到这个目的的呢？
I was given the task of documenting an application that has no comments. However, I have been unable to understand the following function.
private uint GetVersionHash(int encver, int realver)
{
int EncryptedVersionNumber = encver;
int VersionNumber = realver;
int VersionHash = 0;
int DecryptedVersionNumber = 0;
string VersionNumberStr;
int a = 0, b = 0, c = 0, d = 0, l = 0;
VersionNumberStr = VersionNumber.ToString();
l = VersionNumberStr.Length;
// I am specifically struggling with the purpose and intent of this loop.
for (int i = 0; i < l; i++)
{
VersionHash = (32 * VersionHash) + (int)VersionNumberStr[i] + ;
}
a = (VersionHash >> 24) & 0xFF;
b = (VersionHash >> 16) & 0xFF;
c = (VersionHash >> 8) & 0xFF;
d = VersionHash & 0xFF;
DecryptedVersionNumber = (0xff ^ a ^ b ^ c ^ d);
if (EncryptedVersionNumber == DecryptedVersionNumber)
{
return Convert.ToUInt32(VersionHash);
}
else
{
return 0;
}
}
With my current understanding it bitshift 5 right and adds some value.
Also some further information:
encverappears to be an encrypted version as an int (it is read from a file)realverseems to be version we are testing for match. It is looped in another function to this function fromshort.MinValuetoshort.MaxValue
What is the purpose of this loop? How does the code achieve this purpose?
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该循环正在计算表示真实版本号的字符串中的字符（数字）的“哈希”。 VersionHash 的值是一个数字，取决于字符串中的每个字符、字符串的长度及其顺序。
The loop is calculating a 'hash' of the characters (digits) in the string representing the real version number. The value of VersionHash is a number which depends on every character in the string, the length of the string, and their order.
在我看来，for 循环只是自定义哈希函数的一部分 - 用于生成方法参数 int encver 的函数相同，因为该方法的本质是测试 encver 中的哈希是否与 realver 的重新哈希相匹配- 大概是为了某种完整性检查。
To me it looks like the for loop is just part of a custom hash function - the same function that was used to generate the method param int encver, as the essence of the method is to test that the hash in encver matches a rehash of realver - presumably for some kind of integrity check.
我不会太担心这个例程中的逻辑。这是一个典型的国产加密系统，用于返回版本号的“散列”。我会在注释中概括该例程，指出该函数，而不会涉及太多细节。
for 循环通过获取字符串中字符的 (int) 值来生成哈希，然后执行相当于将其左移 4 个字节的操作。因此假设版本号的(int)值为：
1,2,3for
循环将生成VersionHash为：
000200030004
I wouldn't worry too much about the logic in this routine. This is a typical home grown encryption system to return a "hash" of the version number. I would blanket the routine in a comment that indicated the function without going into too much detail.
The for loop is generating a hash by getting the (int) value of a character in the string and then doing the equivalent of shifting it left by 4 bytes. So assuming that the (int) values of the version number are:
1, 2, 3
The for loop will generate a VersionHash of:
000200030004