2.3将常数e（2.718281828）作为常量定义，然后

1、#include<iostream>#include<坡纠课柩iomanip>using namespace std;int main(){ double e = 2.718281828; cout << setprecision(10) << e << endl; cout << setiosflags(ios::fixed) << setprecision(8) << e << endl; system("pause");}

2、#include<iostream>#include<iomanip>using namespace std;int main(){double e = 2.718281828;cout << setiosflags(ios::scientific) << setprecision(8) << e << endl;system("pause");}