//天氣
#include<stdlib.h>		//exit()函數的定義
#include<iostream.h>
#include<fstream.h>		//IO所需庫
#define FILE_IN "weather.in"
#define FILE_OUT "report.out"

float FindAve(float[],int);

void HighLow(float[],float[],float*,float*,int);

void main()
{
	float high[31],low[31],high_ave,low_ave,hottest,coldest;
	char date[25],location[100];
	int total_days,i=0;

	//先定義輸入輸出流
	ifstream input;		//輸入流對象
	ofstream output;	//輸入流對象

	//打開文件用于讀數據，如果文件不在，不要創建文件
	input.open(FILE_IN,ios::in|ios::nocreate);

	//檢查文件是否打開。另外一種方法是利用fail函數
	if(!input)
	{
		cout<<"\n未找到輸入文件"<<FILE_IN;
		cout<<"\n退出程序，再見！\n";
		exit(1);
	}
	output.open(FILE_OUT,ios::out);
	cout<<"\n文件找到，繼續執行……";

	//讀入兩行，并存入字符串中
	input.getline(date,24);
	input.getline(location,49);

	cout<<location<<endl;

	while(!input.eof())		//一直讀到文件結束
	{
		input>>high[i]>>low[i];	//文件指針位置必須無誤，不能出現非預期數據
		++i;
	}

	total_days=i-1;		//溫度記錄的天數為i
	
	cout<<"\n讀數據完畢"<<endl;

	high_ave = FindAve(high,total_days);
	low_ave = FindAve(low,total_days);
	HighLow(high,low,&hottest,&coldest,total_days);

	//向輸出文件寫數據
	output<<"Monthly Weather Report\n\nLocation:\t"<<location
			<<"\nDate:"<<date;
	output<<"\n\nAverage Temperatures:High "<<high_ave
		<<", low "<<low_ave;
	output<<"\n\nHottest Temperature:\t"<<hottest
		<<"\nColdest Temperature:\t"<<coldest;

	input.close();
	output.close();
}

float FindAve(float x[],int total)
{
	float sum=0.0;
	int i;
	for(i=0;i<total;++i)
	{
		sum+=x[i];
	}
	return (sum/total);
}

void HighLow(float high[],float low[],float *h,float *l,int total)
{
	*h=high[0],*l=low[0];
	int i;

	//遍歷兩個數組，尋找最大值……
	for(i=0;i<total;++i)
	{
		if(high[i]>*h)*h=high[i];
		if(low[i]<*l)*l=low[i];
	}
}