C++基础（1）

#include <iostream>using namespace  std;# define PI 3.1415926#define NEWLINE '\n'int main(){    /* code */    double r = 5.0;    double circle;    int foo = 0;    auto bar = 8;    decltype(foo) dog = 9;    cout << "bar is:\n"<<bar<<endl;    cout<<"dog is:\n"<<dog<<endl;    circle = 2 * PI * r;    cout << circle;    cout << NEWLINE;    return 0;}