在: http : //www.learncpp.com/cpp-tutorial/19-header-files/ 提到以下内容: add.cpp: int add(int x, int y) { return x + y; } main.cpp中: #include <iostream> int add(int x, int y); // forward declaration using function prototype int main() { using namespace std; cout << "The sum of 3 and 4 is " << add(3, 4) << endl; return 0; } […]