C++随机点名程序

Question

#include <iostream>
#include <string>
#include <fstream>
#include <ctime>
using namespace std;
class Class;
class Student{
string Name;//学生姓名
string ID;//学生学号
string Number;//学生序号
public:
string GetName();
string GetNumber();
string GetID();
friend class Class;
};
string Student::GetID()
{
return ID;
}
string Student::GetName()
{
return Name;
}
string Student::GetNumber()
{
return Number;
}
class System
{
public:
void menu();
};
class Class{
Student *student;
int number;
public:
Class(string);
~Class(){delete []student;};
int GetNumber();
friend void System::menu();
};

void System::menu()
{
string temp;
cout<<"请输入学生名单文件（*.txt）的全路径（输入exit为退出本程序）：";
cin>>temp;
if(temp=="exit")exit(0);
Class cls(temp);
char tmp,tp;
loop: cout<<"Enter 1 or 0<1抽取，0退出，其它无效>：";
cin>>tmp;
if(tmp=='1')
{
int NUM;//被选中学生的号码
time_t NowTime;
again: NowTime=time(NULL);//利用系统时间
NowTime=NowTime%cls.GetNumber();//用取余的方式求出NUM
NUM=NowTime;
cout<<"被抽中的是："<<endl;
cout<<"学生序号："<<cls.student[NUM].GetNumber()<<endl;
cout<<"学生学号："<<cls.student[NUM].GetID()<<endl;
cout<<"学生姓名："<<cls.student[NUM].GetName()<<endl;
againchoose: cout<<"Enter 1 or 0<1为继续抽取，0为退出，其它无效>：";
cin>>tp;
if(tp=='1')goto again;
else if(tp=='0')exit(0);
else goto againchoose;
}
else if(tmp=='0')exit(0);
else goto loop;
}
Class::Class(string temp)
{
string tmp;
number=0;
char *p=new char[100];
while(1)
{
fstream File;
File.open(temp.c_str());
if(File.is_open())
{
cout<<"文件打开成功......"<<endl;
while(!File.eof()){File.getline(p,100);number++;}
cout<<number<<endl;
student=new Student[number];
File.seekg(0, ios_base::beg);
for(int i=0;i<number;i++){
File>>tmp;
student[i].Number=tmp;
File>>tmp;
student[i].ID=tmp;
File>>tmp;
student[i].Name=tmp;
}
File.close();
break;
}
else
{
cout<<"Warnning:Cannot open this file!"<<endl;
File.close();

}
}
cout<<"已经初始化....."<<endl;
cout<<"该班学生人数为："<<number<<"人"<<endl;
}
int Class::GetNumber()
{
return number;
}
int main()
{
System sys;
sys.menu();
return 0;
}

txt文件内容为
1 2 ss
2 4 aa

Answer 1

//当文件流为eof状态时需先clear再seek
#include <iostream>
#include <string>
#include <fstream>
#include <ctime>
using namespace std;
class Class;
class Student{
string Name;//学生姓名
string ID;//学生学号
string Number;//学生序号
public:
string GetName();
string GetNumber();
string GetID();
friend class Class;
};
string Student::GetID()
{
return ID;
}
string Student::GetName()
{
return Name;
}
string Student::GetNumber()
{
return Number;
}
class System
{
public:
void menu();
};
class Class{
Student *student;
int number;
public:
Class(string);
~Class(){delete []student;};
int GetNumber();
friend void System::menu();
};

void System::menu()
{
string temp;
cout<<"请输入学生名单文件（*.txt）的全路径（输入exit为退出本程序）：";
cin>>temp;
if(temp=="exit")exit(0);
Class cls(temp);
char tmp,tp;
loop: cout<<"Enter 1 or 0<1抽取，0退出，其它无效>：";
cin>>tmp;
if(tmp=='1')
{
int NUM;//被选中学生的号码
time_t NowTime;
again: NowTime=time(NULL);//利用系统时间
NowTime=NowTime%cls.GetNumber();//用取余的方式求出NUM
NUM=NowTime;
cout<<"被抽中的是："<<endl;
cout<<"学生序号："<<cls.student[NUM].GetNumber()<<endl;
cout<<"学生学号："<<cls.student[NUM].GetID()<<endl;
cout<<"学生姓名："<<cls.student[NUM].GetName()<<endl;
againchoose: cout<<"Enter 1 or 0<1为继续抽取，0为退出，其它无效>：";
cin>>tp;
if(tp=='1')goto again;
else if(tp=='0')exit(0);
else goto againchoose;
}
else if(tmp=='0')exit(0);
else goto loop;
}
Class::Class(string temp)
{
string tmp;
number=0;
char *p=new char[100];
while(1)
{
ifstream File;
File.open(temp.c_str());
if(File.is_open())
{
cout<<"文件打开成功......"<<endl;
while(!File.eof()){File.getline(p,100);number++;}
cout<<number<<endl;
student=new Student[number];
File.clear(); // must clear when the stream is in the eof statue!!!
File.seekg(0);
cout << p << endl;
for(int i=0;i<number;i++){
File>>tmp;
student[i].Number=tmp;
File>>tmp;
student[i].ID=tmp;
File>>tmp;
student[i].Name=tmp;
}
File.close();
break;
}
else
{
cout<< "Warnning:Cannot open this file!" <<endl;
File.close();

}
}
cout<<"已经初始化....."<<endl;
cout<<"该班学生人数为："<<number<<"人"<<endl;
}
int Class::GetNumber()
{
return number;
}
int main()
{
System sys;
sys.menu();
return 0;
}

Answer 2

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