C程序编号没有正确排序数组

Question

I have an array of structs for products that I am trying to sort by name, type, price, and quantity. Name and type work, but price and quantity aren't working. My code is:

else if (sort == sortByPrice)
{
    for (int i = 0; i < numProducts; i++)
    {
        int smallPosition = i;
        for (int x = i + 1; x < numProducts; x++)
        {
            if (list[i].price > list[x].price)
            {
                smallPosition = x;
            }
        }

        temp = list[i];
        list[i] = list[smallPosition];
        list[smallPosition] = temp;
    }

}
else if (sort == sortByQty)
{
    for (int i = 0; i < numProducts; i++)
    {
        int smallPosition = i;
        for (int x = i + 1; x < numProducts; x++)
        {
            if (list[i].qty > list[x].qty)
            {
                smallPosition = x;
            }
        }

        temp = list[i];
        list[i] = list[smallPosition];
        list[smallPosition] = temp;
    }
}

Can anyone tell me why it doesn't work/how to fix it?

Answer 1

Following up on Lee Daniel Crocker 's comment, you should dynamically compare with the value at smallPosition instead of i so that it will always point to the smallest remaining item:

    int smallPosition = i;
    for (int x = i + 1; x < numProducts; x++)
    {
        if (list[smallPosition].price > list[x].price)
        {
            smallPosition = x;
        }
    }

Answer 2

You should move the swap code inside the if statement:

for (int i = 0; i < numProducts; i++)
{
    for (int x = i + 1; x < numProducts; x++)
    {
        if (list[i].price > list[x].price)
        {
            temp = list[i];
            list[i] = list[X];
            list[X] = temp;
        }
    }

}

Answer 3

Just use bubble sort.

In the bubble sort you swap the values of the current value is bigger than the next one, if you do this action until you get to the end of the array then the array will be sorted.