c++中文件输入/输出简单示例

下边的程序演示了用户输入信息，然后将信息显示到屏幕上，再将这些信息写到文件中，读者可以使用文本编辑器来查看该输出文件中的内容。

#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。