::没有命名空间 [英] :: without a namespace

问题描述

我在看这个C ++代码：

I am looking at this C++ code:

https://github.com/cinder/Cinder/blob/renderStringBox/src/cinder/gl/TextureFont.cpp

我不知道这行中使用的语法是什么。如何在之前没有指定命名空间::？这是否意味着它使用与您所在的类相同的命名空间？

I am not sure what's the syntax being used in this line. How come there's no namespace specified before :: ? Does that mean it's using the same namespace as the class you're in?

::CGContextRef cgContext = cocoa::createCgBitmapContext( surface );

推荐答案

:: :: CGContextRef 表示全局命名空间，这意味着 CGContextRef p>

:: in ::CGContextRef means global namespace, which means CGContextRef is defined in the global namespace.

int x = 10; 
namespace test
{
    int x = 100;
    void f() 
    {
         std::cout << x << std::endl;  //prints 100
         std::cout << ::x << std::endl; //prints 10
    }     
}

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