如何从 n1 命名空间访问 y(位于命名空间 n2 内): 测试代码如下:
#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;
}
我遇到以下错误: test.cpp:7:15: 错误: ‘::n2’ 尚未声明 int m =::n2::y;
最佳答案
只需更改顺序,使 n2 在 n1 中可解析:
#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;
}
关于c++ - 将一个命名空间数据成员访问到另一个,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48335093/