Question

I want to get characters of a string pointed by a position memory pointer in native C++:

For an equivalent implementation in C#, it will be:

int positionMemory = getPosition();

long size = 10;

string result = Marshal.PtrToStringAnsi(new IntPtr(positionMemory), size);

How can I produce the result in C++?

Answer 1

I have a feeling this is going to cause problems down the road…

The following should be more or less equivalent to the C# snippet you gave with the exception that the resulting string (stored in result) will still be ‘ANSI’ – it is not widened to UNICODE as would occur in the C# snippet.

int positionMemory = getPosition();
long size = 10;

std::string result( reinterpret_cast<const char *>(positionMemory), size);

Note that size characters will be placed in result – including '/0' characters, so if you try to pass the string to something expecting a C-style sting using c_str() you may get some unexpected results.

Also, the usual caveats about using an int as a pointer (especially if you want this to have a hope of working on a 64-bit system) apply.