包含流操作算子的头文件是"iomanip"
#include<bits/stdc++.h>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<iomanip>
#define pi acos(1.0)
#define e exp(-1.0)
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pa;
const ll INF=0x3f3f3f3f3f3f3f3f;
int main() {
ios::sync_with_stdio(false);
int n=141;
cout << "1)" << hex << n << ' ' << dec << n << ' ' << oct << n << endl;
double x = 1234567.89, y = 12.3456789;
cout <<"2) "<< setprecision(5) << x << ' ' << y << endl;
cout << "3)" << fixed << setprecision(5) << x << ' ' << y << endl;
cout << "4)" << scientific << setprecision(5) << x << ' ' << y << endl;
cout << "5)" << showpos << setw(12) << setfill('*') << 12.1 << endl;
cout << "6)" << noshowpos << setw(12) << right << 12.1 << endl;
cout << "7)" << noshowpos << setw(12) << left << 12.1 << endl;
cout << "8)" << setw(12) << internal << -12.1 << endl;
cout << "9)" << 12.1 << endl;
return 0;
}