#include <stdio.h> namespace XXX { class A { public: void test() { printf("this is namespace XXX class A\n"); } }; } using namespace XXX; int main() { A* p = new A(); p->test(); return 1; }
相同的命名空间编译时会合并
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#include <iostream> using namespace std; namespace Space { int a = 10; } namespace Space { int b = 20; } using namespace Space; int main() { cout << "a = " << a << endl; cout << "b = " << b << endl; return 0; }