[英]Accessing one namespace data member into another
如何從n1命名空間訪問y(位於n2命名空間內):測試代碼如下:
#include<iostream>
using namespace std;
namespace n1
{
int x = 20;
int m = ::n2::y;
void printx()
{
cout << "n1::x is " << x << endl;
cout << "n2::y is " << m << endl;
}
}
namespace n2
{
int y = 10;
}
int main()
{
cout << n1::x << endl;
n1::printx();
cout << n2::y << endl;
return 0;
}
我得到以下錯誤:test.cpp:7:15:錯誤:':: n2'尚未聲明int m = :: n2 :: y;
只需更改順序,即可在n1內解析n2:
#include<iostream>
using namespace std;
namespace n2
{
int y = 10;
}
namespace n1
{
int x = 20;
int m = n2::y;
void printx()
{
cout << "n1::x is " << x << endl;
cout << "n2::y is " << m << endl;
}
}
int main()
{
cout << n1::x << endl;
n1::printx();
cout << n2::y << endl;
return 0;
}
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