std::vector, why initializer list does not work in C++/CLI

Question

Three simple statements, one does not compile.

std::vector<size_t>({});
std::vector<size_t>({ 1 });  // This does not compile
std::vector<size_t>({ 1, 2 });

Only the second statement with one element in the list brings an error:

cannot convert from 'initializer-list' to 'std::vector<size_t,std::allocator<char32_t>>'

It works fine for char, long, int etc., but not for size_t. Does anybody know why and maybe there is a workaround?

Here is the complete code:

// ConsoleApplication1.cpp : main project file.

#include "stdafx.h"
#include <vector>

using namespace System;

int main(array<System::String ^> ^args)
{
    std::vector<size_t>({});
    std::vector<size_t>({ 1 });
    std::vector<size_t>({ 1, 2 });
    return 0;
}

I'm using the C++/CLI compiler from VS2013

[Works fo](http://coliru.stacked-crooked.com/a/b360341326a33bcf)[r me](http://coliru.stacked-crooked.com/a/a9fb491f977996f3). Where is your [MCVE]? — Lightness Races in Orbit, May 10 '16 at 13:54
Why are you using a size_t as template argument? Wouldn't you use a int or a long? — sergiol, May 10 '16 at 13:55
Possible duplicate of [how-to initialize 'const std::vector' like a c array](http://stackoverflow.com/questions/231491/how-to-initialize-const-stdvectort-like-a-c-array) — Klaus, May 10 '16 at 13:55
@sergiol: Why would you use `int` or `long` when `size_t` is appropriate? — Lightness Races in Orbit, May 10 '16 at 13:55
@Klaus We really need an [mcve] before we can say what the issue is. — NathanOliver, May 10 '16 at 13:56
@Wernfried what version of c++ are you using? If you don't know, what's the compiler version? If you don't know *that*, what version of Visual Studio are you using? — jaggedSpire, May 10 '16 at 13:59
I'm going to put money on the issue being the OP is not using C++11. The error states *'initializer-list'* which is not the same as a `std::initializer_list`. — NathanOliver, May 10 '16 at 14:00
@Wernfried There is a [edit] link on your question you can use to edit the code into the question. Also what compiler are you using? — NathanOliver, May 10 '16 at 14:09
You might want to add the [tag:c++-cli] tag to this, @Wernfried. — jaggedSpire, May 10 '16 at 14:32
In ISO C++ the initializations are correct and use the `initializer_list` constructor of vector. obviously C++/CLI is different — M.M, May 10 '16 at 21:44
There are various kinds of miracles required to get a language extension that was frozen 11 years ago to compile C++11 code. Nevertheless, it works just fine in VS2015. Sure, not in VS2013, work in progress, @Guillaume gives the workaround. Do use the System::Collections::Generic namespace instead so you don't get the worst of both worlds. `List` is a better `vector` — Hans Passant, May 11 '16 at 23:42

score 1 · Answer 1 · answered May 11 '16 at 22:12

The right and proper way to use std::initializer-list is

    std::vector<size_t>{};
    std::vector<size_t>{ 1 };
    std::vector<size_t>{ 1, 2 };

Ie. Without parenthesis. See http://www.stroustrup.com/C++11FAQ.html#init-list for examples.

Using this should fix your issue. Otherwise, in last resort, you can force type like this: std::vector<size_t>( std::initializer-list<size_t>{ 1 } );

std::vector, why initializer list does not work in C++/CLI

1 Answers1