Question

I use the MSVC with STL on VS. The autocomplete suggestions that it gives is giving me grief. Can you please break this suggestion for the std::transform function?

_OutTy * transform<_InIt1, _InTy, _InSize, _OutTy, _OutSize, _Fn2>
(_InIt1 _First1, _InIt1 _Last1, _InTy (&_First2)[_InSize], _OutTy(&_Dest)[_OutSize], _Fn2 _Func)

Edit: I am sorry but I should have been clearer. I saw the transform’s documentation. I wanted someone to break down the various symbols in the above sentence.

Thanks.

Answer 1

_OutTy* // output type   
transform<_InIt1, // input iterator type for first range
          _InTy, _InSize, // input and size type for second range (array)
          _OutTy, _OutSize, // output and size type for output range (array)
          _Fn2> // transformation function object type
(_InIt1 _First1, _InIt1 _Last1, // first and last iterators for first range
 _InTy (&_First2)[_InSize], // array for second range
 _OutTy(&_Dest)[_OutSize], // array for output range
 _Fn2 _Func) // transformation function object

My recommendation: don’t waste your time doing this. It took me several minutes just to break that down myself, and I’m used to this stuff. Get quick access to the docs as suggested in other posts.

If you want to be able to decipher MSVC’s C++ library implementation, it helps to look through their headers rather than just the intellisense. You’ll pick up on some of the common conventions they use, like InIt for input iterator, RanIt for random-access iterator, etc. It’s also essential to understand the basic STL concepts like Sequences, Input Iterators, Bidirectional Iterators, etc. Here’s a rather dated but still nice and carefully worded reference: http://www.sgi.com/tech/stl/table_of_contents.html

The thing to note about this overload is that the second range and output range are arrays whose sizes are deduced automatically, while the first range is specified normally as a couple of iterators pointing to the start and end of the range. Otherwise the first three parameters would be input iterators and the fourth and return type would be an output iterator.