11-7
#include <iostream> using namespace ::std; int main() { ios_base::fmtflags original_flags = cout.flags(); //保存cout参数设置 cout<< 812<<'|'; cout.setf(ios_base::left,ios_base::adjustfield); //设置cout的对齐方式为左对齐 cout.width(10); //将cout宽度改为10 cout<< 813 << 815 << '/n'; cout.unsetf(ios_base::adjustfield); //取消cout对齐方式的设置 cout.precision(2);// 设置浮点数输出的精度值 cout.setf(ios_base::uppercase|ios_base::scientific); //设置浮点数的显示参数 cout << 831.0 ; cout.flags(original_flags); //恢复cout原参数设置 return 0; }运行结果 
源码：
#include<iostream> #include<string> #include<fstream> #include<vector> #include<ctime> #include<cstdlib> using namespace std; class student{ public: int num; string name; long long id; string group; }; int main(){ ifstream fin("list.txt"); student temp; vector<student> stu; while(fin>>temp.num>>temp.id>>temp.name>>temp.group){ stu.push_back(temp); } ofstream fout("roll.text",ios::out); srand((unsigned)time(NULL)); for(int i=0;i<5;i++){ int t=rand()%(stu.size()); cout<<stu[t].num<<" "<<stu[t].id<<" "<<stu[t].name<<" "<<stu[t].group<<endl; fout<<stu[t].num<<" "<<stu[t].id<<" "<<stu[t].name<<" "<<stu[t].group<<endl; } return 0; }
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文章来源: 实验7