输出数据到文本ofstream和从文本中读取数据ifstream

#include <iostream>
#include <fstream>
int main()
{
using namespace std;

char automobile[50];
int year;
double a_price;
double d_price;

ofstream outFile;
outFile.open("tianshuai.txt");

cout<<"Enter the make and model of automobile:";
cin.getline(automobile,50);
cout<<"Enter the model year:";
cin>>year;
cout<<"Enter the original asking price:";
cin>>a_price;
d_price=09.13*a_price;

cout<<fixed;//输出浮点数形式输出变量
cout.precision(2);//设置精度 为小数点后两位
cout.setf(ios_base::showpoint);//强制显示 小数点
cout<<"Make and model:"<<automobile<<endl;
cout<<"Year:"<<year<<endl;
cout<<"Was asking {1}quot;<<a_price<<endl;
cout<<"Now asking {1}quot;<<d_price<<endl;

outFile<<fixed;
outFile.precision(2);
outFile.setf(ios_base::showpoint);
outFile<<"Make and model:"<<automobile<<endl;
outFile<<"Year:"<<year<<endl;
outFile<<"Was asking {1}quot;<<a_price<<endl;
outFile<<"Now asking {1}quot;<<d_price<<endl;

outFile.close();//程序使用完文件后关闭
return 0;
}

#include <iostream>
#include <fstream>
#include <cstdlib>
const int SIZE=60;
int main()
{
using namespace std;
char filename[SIZE];
ifstream inFile;

cout<<"Enter name of data file:";
cin.getline(filename,SIZE);
inFile.open(filename);//打开文件
if(!inFile.is_open())//如果打不开文件
{
cout<<"Could not open the file "<<filename<<endl;
cout<<"Program terminating.\n";
exit(EXIT_FAILURE);
}
double value;
double sum=0.0;
int count=0;

inFile>>value;//读取文件中数值
while(inFile.good())
{
++count; //数值个数
sum+=value;//求数值总和
inFile>>value;//继续读取数值
}
if(inFile.eof())//文件结尾
cout<<"End of file reached.\n";
else if(inFile.fail())
cout<<"Input terminated by data mismatch.\n";
else
cout<<"Input termiated for unknown reason.\n";
if(count==0)
cout<<"No data processed .\n";
else
{
cout<<"Items read:"<<count<<endl;
cout<<"Sum:"<<sum<<endl;
cout<<"Average:"<<sum/count<<endl;
}

inFile.close();

return 0;
}