Question

Strange how I can do it in C++,but not in C#.

To make it clear,i’ll paste the two functions in C++ and then in C# and mark the problematic lines in the C# code with a comment ‘//error’. What the two function does is encoding the parameter and then add it in to a global variable named byte1seeds.

These are the functions in C++

//Global var:  unsigned char byte1seeds[3];  unsigned long GenerateValue( unsigned long * Ptr ) { unsigned long val = *Ptr; for( int i = 0; i < 32; i++ )     val = (((((((((((val >> 2)^val) >> 2)^val) >> 1)^val) >> 1)^val) >> 1)^val)&1)|((((val&1) << 31)|(val >> 1))&0xFFFFFFFE); return ( *Ptr = val ); }  void SetupCountByte( unsigned long seed ) { if( seed == 0 ) seed = 0x9ABFB3B6; unsigned long mut = seed; unsigned long mut1 = GenerateValue( &mut ); unsigned long mut2 = GenerateValue( &mut ); unsigned long mut3 = GenerateValue( &mut ); GenerateValue( &mut ); unsigned char byte1 = (mut&0xFF)^(mut3&0xFF); unsigned char byte2 = (mut1&0xFF)^(mut2&0xFF); if( !byte1 ) byte1 = 1; if( !byte2 ) byte2 = 1; byte1seeds[0] = byte1^byte2; byte1seeds[1] = byte2; byte1seeds[2] = byte1; } 

Now the C# code:

I’ve changed the function GenerateValue.Instead of having a pointer as a parameter, it has a ulong parameter.

To call it and change both values i use:

1. ulong mut1 = GenerateValue(mut);
2. mut = mut1;

Here are the translated functions(the problematic lines are marked with ‘//error’);

//Global var: public static byte[] byte1seeds = new byte[3];  public static ulong GenerateValue(ulong val) {     for( int i = 0; i < 32; i++ )         val = (((((((((((val >> 2)^val) >> 2)^val) >> 1)^val) >> 1)^val) >> 1)^val)&1)|((((val&1) << 31)|(val >> 1))&0xFFFFFFFE);     return val ; }  public static void SetupCountByte( uint seed ) {     if( seed == 0 ) seed = 0x9ABFB3B6;     ulong mut = seed;     ulong mut1 = GenerateValue(mut);     mut = mut1;     ulong mut2 = GenerateValue(mut);     mut = mut2;     ulong mut3 = GenerateValue(mut);     mut = mut3;     mut = GenerateValue(mut);     byte byte1 = (mut & 0xFF) ^ (mut3 & 0xFF); //error     byte byte2 = (mut1 & 0xFF) ^ (mut2 & 0xFF); //error     if( byte1 != 0 )         byte1 = 1;     if( byte2 != 0 )         byte2 = 1;     byte1seeds[0] = byte1^byte2; //error     byte1seeds[1] = byte2;     byte1seeds[2] = byte1; } 

The error is:

Cannot implicitly convert type ‘ulong’ to ‘byte’. An explicit conversion exists (are you missing a cast?)

edit:the error at problematic line 3 is:

Cannot implicitly convert type ‘int’ to ‘byte’. An explicit conversion exists (are you missing a cast?)

Here comes the question: How to solve those errors?

Thanks in advance!

Answer 1

Add a (byte) to cast it. As you could lose precision, you have to tell the compiler that the value will fit into a byte, i.e.

byte byte1 = (byte)((mut & 0xFF) ^ (mut3 & 0xFF)); byte byte2 = (byte)((mut1 & 0xFF) ^ (mut2 & 0xFF));