Question

the line ‘if(arg2 & 1)’ in C++(arg2 is DWORD) is equal to ‘if(arg2 & 1==0)’ in C#(arg2 is Uint32),right?

I am trying to translate a function from C++ to C#,but I get an error:

Operator '&' cannot be applied to operands of type 'uint' and 'bool' 

I’d be also thankful if you could see further in the whole function for any other mistakes.

C++

DWORD Func_X_4(DWORD arg1, DWORD arg2, DWORD arg3) { LARGE_INTEGER result = {1, 0}; LARGE_INTEGER temp1 = {0}; LARGE_INTEGER temp2 = {0}; LARGE_INTEGER temp3 = {0}; LARGE_INTEGER temp4 = {0}; for(int x = 0; x < 32; ++x) {     if(arg2 & 1)     {         temp1.LowPart = arg3;         temp1.HighPart = 0;         temp2.QuadPart = temp1.QuadPart * result.QuadPart;         temp3.LowPart = arg1;         temp3.HighPart = 0;         temp4.QuadPart = temp2.QuadPart % temp3.QuadPart;         result.QuadPart = temp4.QuadPart;     }     arg2 >>= 1;     temp1.LowPart = arg3;     temp1.HighPart = 0;     temp1.QuadPart *= temp1.QuadPart;     temp2.LowPart = arg1;     temp2.HighPart = 0;     temp3.QuadPart = temp1.QuadPart % temp2.QuadPart;     arg3 = temp3.LowPart;     if(!arg2)         break; } return result.LowPart; } 

Converted to C#

LARGE_INTEGER structure:

[StructLayout(LayoutKind.Explicit, Size = 8)] public struct LARGE_INTEGER {     [FieldOffset(0)]     public Int64 QuadPart;     [FieldOffset(0)]     public UInt32 LowPart;     [FieldOffset(4)]     public Int32 HighPart; } 

Function:

public static UInt32 X4(UInt32 arg1, UInt32 arg2, UInt32 arg3)     {         LARGE_INTEGER result = new LARGE_INTEGER();         result.LowPart = 1;         result.HighPart = 0;         LARGE_INTEGER temp1 = new LARGE_INTEGER();         LARGE_INTEGER temp2 = new LARGE_INTEGER();         LARGE_INTEGER temp3 = new LARGE_INTEGER();         LARGE_INTEGER temp4 = new LARGE_INTEGER();         for (int x = 0; x < 32; ++x)         {             if (arg1 & 1 ==0)             {                 temp1.LowPart = arg3;                 temp1.HighPart = 0;                 temp2.QuadPart = temp1.QuadPart * result.QuadPart;                 temp3.LowPart = arg1;                 temp3.HighPart = 0;                 temp4.QuadPart = temp2.QuadPart % temp3.QuadPart;                 result.QuadPart = temp4.QuadPart;             }             arg2 >>= 1;             temp1.LowPart = arg3;             temp1.HighPart = 0;             temp1.QuadPart *= temp1.QuadPart;             temp2.LowPart = arg1;             temp2.HighPart = 0;             temp3.QuadPart = temp1.QuadPart % temp2.QuadPart;             arg3 = temp3.LowPart;             if (arg2==0)                 break;         }         return result.LowPart;     } 

This is what I’m not sure yet:

1. Whether a DWORD in C++ is UInt32 or Int32 in C#?
2. if(integer & integer) means if(integer and integer ==0)? //this is where the error i described above is placed.
3. if(!integer) means if(integer != 0)?
4. Why operator & cannot be used logically in C# ,meaning it requires a boolean?
5. ‘LARGE_INTEGER result = {1, 0}’ means result.lowpart is 1 and result.highpart is 0 or result.Quadpart = 1?

Thanks in advance!

Answer 1

Where you write :

if (arg1 & arg2==0)

The compiler understands :

if (arg1 & (arg2==0)) 

You should write :

if ((arg1 & arg2) == 0) 

This is the way the C++ statement should be translated to C# :

if (arg2 & 1) // C++ (arg2 is DWORD) if ((arg2 & 1) != 0) // C# (arg2 is Uint32) 

Or, in a more generic way:

if (Flags & FlagToCheck) // C++ if ((Flags & FlagToCheck) != 0) // C# 

---

In C/C++, 0 is false, everything else is true.

1. You should check the definition of DWORD, it should be (unsigned int), which is UInt32 in C#
2. if (integer & integer), in C/C++ means ‘if the result of the bitwise and between the two integers is not 0’ (0 is false, everything else is true).
3. if (!integer) means if (integer == 0) (again, 0 is false, everything else is true)
4. in C#, like in Java I think, booleans and numbers are two different things, you can only use booleans in ‘if’ statements, there is not implicit conversion if you use an int : it won’t compile.
5. I’ll leave this one to someone else, I’d need to test to be sure…