#include"iostream" using namespace std; void main01() { //printf("hello_world\n"); cout << "hello_world\n" << endl;//在c++里面输出 system("pause"); }
//求圆的面积 //用面向过程的方法求解了圆形的面积 void main() { double r = 0; double s = 0; //printf("hello_world\n"); cout << "请输入圆的半径:"; cin >> r; //cin代表标准输入 cout << "r的值是:" << r << endl; s = 3.14*r*r; cout << "圆形的面积是s=" << s << endl; system("pause"); }
//面向对象的思路解决这问题 class CirCle { private: double m_s; double m_r; double m_c; public: void setR(double r) { this->m_r = r; } double getR() { return this->m_r; } double getS() { return this->m_r * m_r * 3.14; } double getC() { return this->m_r * 2 * 3.14; } }; int main() { CirCle c1, c2; double r,r2; cout << "输入c1圆的半径" ; cin >> r; c1.setR(r); cout << "c1圆的面积是" << c1.getS() <<endl; cout << "c1元的周长是" << c1.getC() << endl; cout << "输入c2圆的半径" ; cin >> r2; c2.setR(r2); cout << "c2圆的面积是" << c2.getS() << endl; cout << "c2元的周长是" << c2.getC() << endl; system("pause"); return 0; }
c++中的命名空间
#include "iostream" using namespace std; //定义命名空间 namespace namespaceA { int a = 10; } namespace namespaceB { int a = 20; } //使用命名空间 void main() { using namespace namespaceA; cout << a << endl; cout << namespaceB::a << endl; system("pause"); }