c++下将数字已十进制、八进制、十六进制输出

#include<iostream>

using namespace std;

int main(){
//Specifying formats with manipulators
cout<<"a number in decimal:"<<dec<<15<<endl;			//十进制
cout<<"in octal:"<<oct<<15<<endl;						//八进制
cout<<"in hex:"<<hex<<15<<endl;							//十六进制
cout<<"a float-point number:"<<3.1415<<endl;			//float
cout<<"non-printing char (escape):"<<char(27)<<endl;	//ASCII
//return 0;
}