would always compile cleanly and also explicitly states that your conversion from std::vector::size_type to int was intended. Note that if the size of the vector is greater than the biggest number an int can represent, size will contain an implementation defined (de facto garbage) value.

Oct 3, 2011 · vector<double>::size_type vector_size; vector_size = myVector.size(); Whereas in Java you might do. int vector_size; vector_size = myVector.size(); Both are inferior options in C++. The first is extremely verbose and unsafe (mostly due to implicit promotions). The second is verbose and extremely unsafe (due to number range). In C++, do

Mar 3, 2010 · I think John means that if you want some idea how much memory the vector (and contents) occupies, you should be looking at the capacity, not the size. "in-memory size of the container and its elements" is of course ambiguous, but I suspect it's more likely to be understood as relating to the amount of memory allocated by the vector, rather than the amount of that …

Oct 3, 2012 · vector( size_type count, const T& value, const Allocator& alloc = Allocator()); explicit vector( size_type count ); cppreference.com is a much better reference as compared to cplusplus.com. Share

What are the advantages (if any) of initializing the size of a C++ vector as well as other containers? Is there any reason to not just use the default no-arg constructor? Basically, are there any

Dec 2, 2015 · A different aspect of the 'size' function you might find interesting: on Ubuntu 15.10, g++ 5.2.1, Using a 32 byte class UI224, the sizeof(UI224) reports 32 (as expected)

Oct 21, 2011 · It seems like it is a GNU keyword. In GCC's this page, they explain its use with the (vector_size(16)) attribute, saying: int foo __attribute__ ((vector_size (16))); causes the compiler to set the mode for foo, to be 16 bytes, divided into int sized units.

Oct 11, 2010 · If a compiler is not able to prove that the vector size is preserved (which, generally, is very difficult or even infeasible, such as in our case), then you will end up with unnecessary load and sub (and, possibly, shift) instructions. The generated assembly of the loop with GCC 9.2, -O3, and x64 was:

3.4.3 Qualified name lookup [basic.lookup.qual] 1 The name of a class or namespace member or enumerator can be referred to after the :: scope resolution operator (5.1) applied to a nested-name-specifier that denotes its class, namespace, or enumeration.

Jan 8, 2012 · With respect to the practically correct: the "best" approach to implementing std::vector<T> is to have the actually object store a pointer to T which is a pointer to the start of the elements and have the controlling data (the std::vector<T>'s size, capacity, and allocator) immediately precede the values.