Question

我正在尝试在动态数组中找到中间数字。用户输入三个数字，然后程序将其从最小到最大排序。它工作正常，直到我输入数字10,20,30它输出10,10,30当我输入30,20,10它输出10,30,30。

这是我的代码的一部分。感谢

cout << "Enter 3 values and I will sort them from lowest to highest." << endl;

for (index = 0; index < 3; index++)
{
    cin >> number[index];

    while (cin.fail())//Check that values entered are the correct type.
    {
        cout << "You did not enter a number" << endl;
        cout << "Enter a new number." << endl;
        cin.clear();//Clears the input if user input non-integer value.
        cin.ignore(1000, '\n');//Ignores up to 1000 characters or up to new line.

        cin >> number[index];
    }//end while
}//end for

cout << "You have entered the values" << endl;
for (index = 0; index < 3; index++)
{
    cout << number[index] << " ";
    cout << endl;
}//end for

small = number[0];
mid = number[0];
high = number[0];

for (int i = 0; i < 3; i++)//Goes through the array to determine order of values.
{
    if (small > number[i])
    {
        small = number[i];
    }
    else if (high < number[i])
    {
        high = number[i];
    }
    else if (high > mid && mid > small)
    {
        mid = number[i];
    }

}

cout << "Here is the new order of your numbers." << endl;
cout << small << endl;
cout << mid << endl;
cout << high << endl;

Answer 1

更一般地说，您可以使用std::sort中的<algorithm>，但它会修改您的数组（如果您想保留原始输入，请复制一份）。

#include <cstdio>
#include <algorithm>

int main()
{
    int nums[] = {5, 1, 7};
    unsigned int num_size = sizeof(nums)/sizeof(nums[0]);

    std::sort(nums, nums+num_size);

    std::cout << "Here is the order of your numbers:" << std::endl;
    for (unsigned int i=0; i<num_size; ++i)
        std::cout << nums[i] << std::endl;

    return 0;
}

输出：

Here is the order of your numbers:
1
5
7

Answer 2

以下街区中的逻辑存在缺陷

for (int i = 0; i < 3; i++)
{
    if (small > number[i])
    {
        small = number[i];
    }
    else if (high < number[i])
    {
        high = number[i];
    }
    else if (high > mid && mid > small)
    {
        mid = number[i];
    }

}

由于small，med和high未被命令开始。您可以按照@kmac的回答中的建议使用std::sort。如果您想自己编写代码，请尝试：

for (int i = 0; i < 3; i++)
{
   if (small > number[i])
   {
      small = number[i];
   }

   if (high < number[i])
   {
      high = number[i];
   }
}
for (int i = 0; i < 3; i++)
{
   if ( number[i] > small && number[i] < high )
   {
      mid = number[i];
   }
}

Answer 3

当你检查'mid'时，问题是你的第三个if-case，这永远不会是真的，因为你认为高是30，但你还没有检查数字[2] =='30'。

而是写这样的东西

// first find max,min
for (int i = 0; i < 3; ++i)
{
  if (number[i] < small)
  {
    small = number[i];
  }
  if (number[i] > high) 
  {
    high = number[i];
  }
}
// then find mid
for (int i = 0; i < 3; ++i)
{
  if (number[i] > small && number[i] < high)
  {
    mid = number[i];
  }
}

在动态数组C ++中查找中间数

3 个答案: