c++ - 不支持成员聚合初始值设定项列表？

Question

struct bar { int x; };

struct qux
{
    static const int foo[3] = { 1, 2, 3 }; // Error

    static const bar baz = { 0 }; // Error
};

Visual Studio 2008；标准;

syntax error : '{'

Answer 1

只有整数static 非聚合成员可以在类中初始化。所有其他静态 成员(聚合或其他)必须在类外初始化。

//tag.h

struct tag
{
    static const int foo[3];  //aggregate
    static const bar baz;    //aggregate
    static const std::string s; //non-aggregate (non-integral type)
    static const int x = 10; //ok : non-aggregate (integral type)
};

//tag.cpp

const int tag::foo[3] = { 1, 2, 3 }; //ok
const bar tag::baz = { 0 }; //ok
const std::string s = "example"; //ok
const int tag::x; //definition - if you want to take its address