Java解密代码转C#失败求助：修复代码转换后的报错问题

Let's walk through each error you're facing, fix them, and also correct a critical logic mistake that would have broken decryption even if the compiler errors were resolved:

Error 1: 'string' does not contain a definition for 'valueOf' #

Java's String.valueOf() method doesn't exist in C#. Instead of converting the character to a string then parsing it to an integer, you can directly cast the char to an int to get its ASCII/Unicode numeric value. This achieves exactly what your Java code does (since Integer.parseInt(String.valueOf(str.charAt(i))) ultimately retrieves the character's numeric value).

Errors 2 & 3: int.Parse argument mismatches #

Two key issues here:

1. C# Substring behavior differs: Java's substring(startIndex, endIndex) uses start and end positions (exclusive of the end), but C#'s Substring(startIndex, length) takes a start position and the number of characters to extract. Your Java code grabs 2 characters (from i+1 to i+3), so in C# you need str.Substring(i + 1, 2).
2. Parsing hexadecimal strings: To parse a hex string to an int in C#, use Convert.ToInt32(hexString, 16)—this is the direct equivalent of Java's Integer.parseInt(hexStr, 16). The int.Parse overload you tried expects a culture format provider, not a numeric base, which is why those errors appeared.

Critical Logic Mistake #

You accidentally swapped Java's XOR operator (^) with C#'s OR operator (|). These are entirely different operations—XOR is required for your decryption logic to work as intended.

Corrected C# Code #

Here's the fixed button click handler:

private void button1_Click(object sender, EventArgs e)
{
    string str = "575-371-46b-576-362-276-528-634-731-330-53c-729-436";
    str = str.Replace("-", "");
    string result = "";
    
    for (int i = 0; i < str.Length; i += 3)
    {
        // Get numeric value of the first character in the 3-character group
        int charValue = (int)str[i];
        // Parse the next two characters as a hexadecimal integer
        int hexValue = Convert.ToInt32(str.Substring(i + 1, 2), 16);
        // Perform XOR and convert the result back to a character
        result += (char)(hexValue ^ charValue);
    }
    
    textBox1.Text = result;
}

When you run this code, it will correctly decrypt your string to the expected readable result.

内容的提问来源于stack exchange，提问作者amr selim