ofstream mycout(“temp.txt”);//先定義一個(gè)ofstream類對象mycout，括號里面的"temp.txt"是我們用來保存輸出數(shù)據(jù)的txt文件名。這里要注意的是我們的"temp.txt"用的是相對路徑，你也可以寫絕對路徑。
mycout<<“hello”<<endl;//這樣就把"hello"輸出到temp.txt文件中了
mycout.close()；//最后要記得關(guān)閉打開的文件（這里打開的就是temp.txt文件）

#include <iostream>
#include <fstream>//ofstream類的頭文件
using namespace std;
int main()
{
int n;
cin>>n;
ofstream mycout("temp.txt");
mycout<<n<<endl;
mycout.close();
return 0;
}

#include<iostream>
#include<fstream>
using namespace std;
int main()
{
	char automobile[50];
	int year;
	double a_price;
	double b_price;
	ofstream outFile;
	outFile.open("carimfo.txt");//打開文件，或者創(chuàng)建文件，總之就是和一個(gè)文件關(guān)聯(lián)
    //默認(rèn)情況下，open()將首先截?cái)嘣撐募?，即將其長度截短到零——丟棄原有內(nèi)容，將新的輸出加入到文件。
	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;
	b_price = 0.913 * a_price;
	//寫入文件
	outFile << "Make and model: " << automobile << endl;
	outFile << "Year: " << year << endl;
	outFile << "Was asking $" << a_price << endl;
	outFile << "Now asking $" << b_price << endl;
	outFile.close();//關(guān)閉文件
	system("pause");
	return 0;
}

#include<iostream>
#include<fstream>
using namespace std;
int main()
{
	//創(chuàng)建文件輸入對象，并打開
	ifstream inFile;
	inFile.open("carimfo.txt");
	//判斷文件是否打開
	if (!inFile.is_open())
	{
		cout << "Could not open the file carimfo.txt" << endl;
		cout << "Program terminating.\n";
		//函數(shù)exit()終止程序  EXIT_FAILURE用于同操作系統(tǒng)通信的參數(shù)值
		exit(EXIT_FAILURE);
	}
	double value;
	double sum = 0.0;
	int count = 0;
	while (inFile>>value)
	{
		//cout<<value<<endl;
		count++;
		sum += value;
		inFile >> value;
	}
	if (inFile.eof())
		cout << "End of file reached.\n";
	else if (inFile.fail())
		cout << "Input terminated by data mismatch.\n";
	else
		cout << "Input terminated 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();
	system("pause");
	return 0;
}