2017.06.04 c++文件学习

读取文件并计算平均值

最新推荐文章于 2024-12-28 11:26:10 发布

原创最新推荐文章于 2024-12-28 11:26:10 发布 · 253 阅读

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CC 4.0 BY-SA版权

本程序通过读取用户指定的数据文件，逐行解析数字数据，并计算这些数据的总和与平均值。若文件无法打开，则会显示错误信息并终止程序运行。

// a8.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
const int SIZE=60;
int _tmain(int argc, _TCHAR* argv[])
{
	char filename[SIZE];
	ifstream infile;
	cout<<"Enter name of data file:";
	cin.getline(filename,SIZE);
	infile.open(filename);
	if(!infile.is_open())
	{
		cout<<"Cound not open the file :"<<filename<<endl;
		cout<<"Program terminating .\n"<<endl;
		exit(EXIT_FAILURE);
	}
	double value;
	double sum=0.0;
	int count=0;
	infile>>value;
	while(infile.good())
	{
		++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<<"Item read:"<<count<<endl;
		cout<<"Sum:"<<sum<<endl;
		cout<<"Average:"<<double(sum/count)<<endl;
	}
	infile.close();
	return 0;
}