c++中文件输入/输出简单示例

#include <iostream>
#include <fstream>

int main()
{
using namespace std;

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

ofstream outFile;					//creat object for output
outFile.open("carinfo.txt");		//associate with a file

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 = 0.913 * a_price;

//display information on screen with cout

cout << fixed;						//用普通的方式输出浮点数
cout.precision(2);					//指定浮点数的精度
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 $" << a_price << endl;
cout << "Now askiing $" << d_price << endl;

//now do exact same things using outFile instead of cout

outFile << fixed;
outFile.precision(2);
cout.setf(ios_base::showpoint);
cout << "Make and model: " << automobile << endl;
cout << "Year: " << year << endl;
cout << "Was asking $" << a_price << endl;
cout << "Now askiing $" << d_price << endl;

outFile.close();
return 0;
}

在运行程序之前，文件carinfo.txt文件并不存在，在这种情况下，方法open()将新建一个名为carinfo.txt的文件。如果文件存在，默认情况下，open()将丢弃原有的内容，然后将新的输出加到给文件中。