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initializer list in Clang

Tags:

c++

c++11

Today Apple updates Command Line Tools for Xcode and then upgrades clang from 318.0.58 to 318.0.61.

I've tried to use initializer list, but can't compile below code.

#include <iostream>
#include <random>
#include <initializer_list>

int main()
{
    std::mt19937 rng(time(NULL));

    std::initializer_list<double> probabilities =
    {
        0.5, 0.1, 0.1, 0.1, 0.1, 0.1
    };

    std::discrete_distribution<> cheat_dice (probabilities);

    int a[6] = { };

    for ( int i = 0 ; i != 1000; ++i )
    {
        ++a[cheat_dice(rng)];
    }

    for ( int i = 0; i != 6; ++i )
    {
        std::cout << i + 1 << "=" << a[i] << std::endl;
    }
}

Then, I tried to compile.

$ clang++ -stdlib=libc++ foo.cpp

Error log

foo.cpp:9:10: error: no member named 'initializer_list' in namespace 'std'
    std::initializer_list<double> probabilities =
    ~~~~~^
foo.cpp:9:33: error: expected '(' for function-style cast or type construction
    std::initializer_list<double> probabilities =
                          ~~~~~~^
foo.cpp:9:35: error: use of undeclared identifier 'probabilities'
    std::initializer_list<double> probabilities =
                                  ^
foo.cpp:10:5: error: expected expression
    {
    ^
foo.cpp:14:46: error: use of undeclared identifier 'probabilities'
    std::discrete_distribution<> cheat_dice (probabilities);
                                             ^
5 errors generated.

On the other hand, I can compile above code with gcc-4.7.1-RC-20120606.

$ g++ -std=c++11 foo.cpp

Doesn't Apple's clang support initializer list? Clang version:

$ clang++ -v
Apple clang version 3.1 (tags/Apple/clang-318.0.61) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin11.4.0
Thread model: posix
like image 434
user1214292 Avatar asked Jun 12 '12 06:06

user1214292


2 Answers

Try by specifying -std=c++0x (as @jweyrich correctly pointed out) as part of the clang command line. The default for clang is C++98 mode. Initializer lists are a C++11 feature.

Also, from the clang C++98 and C++11 support page you can check the status of various new C++ standard features. For example, initializer lists are available in 3.1 (and above).

like image 147
dirkgently Avatar answered Oct 11 '22 12:10

dirkgently


Compile using the command:

clang++ -stdlib=libc++ -std=c++0x foo.cpp

Note that -std=c++11 also works. In my machine, running:

$ clang --version

results in:

Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin12.2.0
like image 22
Allan Avatar answered Oct 11 '22 10:10

Allan