Using memcpy to copy part of an array, and other memory manipulation tools

Question

Is it possible to use memcpy to copy part of an array?

Say for example we have an array of 10 integers. Can we create a new array, and copy the last 5 integers into it?

Are there other memory/array copying/manipulation tools which are available for use with c/c++?

Answer 1

Is it possible to use memcpy to copy part of an array?

No, it is not possible in the general case. You can only do that when the type of the elements in the array is of trivial layout.

Say for example we have an array of 10 integers. Can we create a new array, and copy the last 5 integers into it?

ints are trivial types, so for that particular case it would work:

int source[10] = { ::: };
int target[5];

std::memcpy( target, source + 5, 5 * sizeof(int) );

Are there other memory/array copying/manipulation tools which are available for use with c/c++?

Sure, the entire set of algorithms in C++ Standard Library will work with arrays. You use pointers to the first and one-past-the-last elements in the array as begin/end iterators. Or if you are using C++11 then just std::begin|end( array ).

std::copy( source + 5, source + 10, target + 0 );

or

std::copy( std::begin(source) + 5, std::end(source), std::begin(target) );

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Here is a metafunction you can use to check whether a type is trivial, along with the definition of such concept: http://en.cppreference.com/w/cpp/types/is_trivial