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Code C sharp


WinniePh

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Hello.I am trying to crack basic crackmes for .NET written on C# that can't undestand code.


Please,explain me some ones. Here is function of button clicking..



private void button1_Click(object sender, EventArgs e)
{
string str = "486752416871754464";
string str2 = "";
while (str.Length > 0)
{
str2 = str2 + Convert.ToChar(Convert.ToUInt32(str.Substring(0, 2), 0x10)).ToString();
str = str.Substring(2, str.Length - 2);
}

What the data it converts in the body of cicle while on str2?


 


 


What is str.substring with agruments(0,2) and 0x10.ToString();?


Could someone explain this code better please?I am just newbie in classes and methods of C#


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Substring is used to remove bits of a string and return that chunk. So in the case of:


str.Substring(0, 2) this means to start at index 0 of str, and take the next two characters and return them as a new string.


 


So in your case, the first time this is called it would be:


"486752416871754464".Substring(0, 2);


 


That would return a string of:


"48"


 


As for:


Convert.ToChar(Convert.ToUInt32(str.Substring(0, 2), 0x10)).ToString();


 


You need to work from the inside out. The first to happen is:


str.Substring(0, 2) which I explained above.


 


Next is:


 


Convert.ToUInt32(str.Substring(0, 2), 0x10)


 


This will convert the number returned from the Substring to a unsigned integer, using base 16 (0x10 is hex for 16).


 


Last is:


Convert.ToChar( .. ).ToString()


 


Which means to convert the number result to a char which is a single letter in C#, then convert that char to a string.


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