filein1.cpp

C++的常用算法

//这个程序在本书所带软盘中，文件名为FILEIN1.CPP
//这个程序演示数值文件的输入。

#include <fstream.h>
#include <stdlib.h>

void main(void)
{
	ifstream in_file;						//定义一个输入文件

	int exam1, exam2, exam3, sum = 0;
	float avg;

	in_file.open("scores.dat", ios::in);	//打开这个文件
	if(!in_file)							//检查文件打开是否成功
	{
		cout << "The file open is fail. Check the disk and try again..." << endl;
		exit(1);
	}

	in_file >> exam1 >> exam2 >> exam3;		//从文件中读入三个数值

	sum = exam1 + exam2 + exam3;
	avg = (float) sum / 3;

	cout << "exam1 = " << exam1 << "  exam2 = " << exam2 << "  exam3 = " << exam3 << endl;
	cout << "sum = " << sum << endl;
	cout << "average = " << avg << endl;

	in_file.close();
}

/*这个程序运行后的一个典型输出结果如下：
exam1 = 89  exam2 = 100  exam3 = 93
sum = 282
average = 94
*/