What is equivalent mmap in C++ for linux?

Question

What is equivalent mmap into C++?

I have code like below

LCDdata = mmap(NULL, iFrameBufferSize, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fb_fd, 0);

Where LCDdata is unsigned char type pointer , iFrameBufferSize is int type and fb_fd is static int type.

When I compile it by use of arm g++ tool chain it give me error as below

error: invalid conversion from 'void*' to 'unsigned char*' [-fpermissive]

So how can I use any equivalent type function instead of mmap ?

Which header file I should include? And how this new line's syntax will become?

Answer 1

The C++ equivalent is auto LCDdata = static_cast<unsigned char*>(mmap(...

In C++ we prefer to define out variables only when we initialize them, and because of that we often don't need to specify the type anymore. Here, we don't need to repeat unsigned char* .

Answer 2

C allows void* to be assigned to pointers of any type without a cast. C++ does not. C programmers have complained about this for ages ( malloc being the most common complaint), but it's not likely to change.

The solution is to add the cast. If the source needs to be compilable as C, use a C-style cast:

LCDdata = (unsigned char*)mmap(...);

Otherwise use a C++ cast

LCDdata = static_cast<unsigned char*>(mmap(...));

If you want to do something more drastic, you could look into Boost Interprocess . That would give you RAII.