c++ - 函数不返回输入数组的最高值和最低值

Question

此函数未准确返回输入到数组中的最高值和最低值。我不确定我为程序输入了什么代码来执行此操作。该程序需要返回输入到数组中的所有元素的平均值(平均部分可以正常工作)，并找到输入到数组中的所有值中的最高值和最低值。请帮忙!

#include <iostream>
using namespace std;
float temptotal = 0;
float averagetemp = 0;
float temperatures[50];
float average(int);
void highest(int);
void lowest(int);
int main()
{
int days = 0;
cout << "Enter the number of days: ";
cin >> days;
if (days > 50)
{
    cout << "You may only enter temperatures for 50 days." << endl;
    return 0;
}
average(days);
highest(days);
lowest(days);
}
float average(int days)
{
    for (int i = 1; i <= days; i++)
    {
        cout << "Enter the temperature for day number " << i << ": ";
        cin >> temperatures[i];
        temptotal += temperatures[i];
    }
        averagetemp = temptotal / days;
        cout << "The average temperature is: " << averagetemp << endl;
        return averagetemp;
}
void highest(int days)
{
    int count;
    int highest;
    highest = temperatures[50];
    for (count = 1; count < days; count++)
    {
        if (temperatures[count] > highest)
            highest = temperatures[count];
        cout << "The highest temperature is: " << highest << endl;
    }
}
void lowest(int days)
{
    int count;
    int lowest;
    lowest = temperatures[50];
    for (count = 1; count < days; count++)
    {
        if (temperatures[count] < lowest)
            lowest = temperatures[count];
        cout << "The lowest temperature is: " << lowest << endl;
    }
}

Answer 1

这个函数

float average(int days)
{
    for (int i = 1; i <= days; i++)
    {
        cout << "Enter the temperature for day number " << i << ": ";
        cin >> temperatures[i];
        temptotal += temperatures[i];
//... 

已经错了，因为元素 temperatures[0]不会被初始化。你必须写

float average(int days)
{
    for (int i = 1; i <= days; i++)
    {
        cout << "Enter the temperature for day number " << i << ": ";
        cin >> temperatures[i-1];
        temptotal += temperatures[i-1];
//... 

或者

float average(int days)
{
    for (int i = 0; i < days; i++)
    {
        cout << "Enter the temperature for day number " << i + 1 << ": ";
        cin >> temperatures[i];
        temptotal += temperatures[i];
//... 

函数 highest和 lowest也错了。例如数组 temperatures没有索引为 50 的元素。此外，用户可以输入小于 50 的天数。所以这个语句

highest = temperatures[50];

错了。

函数可以这样写函数定义

void highest( int days )
{
    int highest = temperatures[0];

    for ( int count = 1; count < days; count++ )
    {
        if ( highest < temperatures[count] ) highest = temperatures[count];
    }

    cout << "The highest temperature is: " << highest << endl;
}

考虑到有标准算法std::max_element , std::min_element , std::minmax_element在 header 中声明 <algorithm>可以用来代替您的函数。

例如可以使用标准算法定义函数 highest std::max_element以下方式

#include <algorithm>

//...

void highest( int days )
{

    cout << "The highest temperature is: " 
         << *std::max_element( temperatures, temperatures + days )
         << endl;
}