在c ++中向数组添加索引和指定数字

Question

我正在制作一个程序，从用户提供的数组的索引中删除一个数字，显示新数组，然后要求用户在他们选择的任何索引处插入一个数字。该程序的第一部分在删除索引时运行良好，但我在添加索引和数字时遇到了麻烦。例如，如果用户从索引 5 中删除数字后的 NEW 数组是：12 34 45 2 8 16 180 182 22，如果您记得数组从 0 开始，这是正确的，那么他们请求例如添加索引 5再次使用数字 78，它变得一团糟。它显示 12 34 45 2 78 8 16 180 182 22 （然后由于某种原因它还输出数字 -858993460？）所以问题基本上是它在它应该之前添加了新索引和第一索引。如果这听起来很令人困惑，我很抱歉，但我已经坚持了几个小时。谢谢！

//This program demos basic arrays

#include <iostream>
using namespace std;

const int CAP = 10;

int main()
{
    int size;
    int list[CAP] = { 12, 34, 45, 2, 8, 10, 16, 180, 182, 22 };
    size = 10;
    int i, delIndex, addIndex, newInt = 0;

    cout << "Your list is: " << endl;
    for (i = 0; i < CAP; i++)
    {
        cout << list[i] << endl;
    } 

//Deleting an index

cout << "\nPlease enter index to delete from: ";
cin >> delIndex;

for (i = delIndex; i <= 10; i++)
{
    list[i] = list[i + 1];

}

cout << "The index position you specified has been deleted." << endl;
cout << "The new array is: " << endl;
for (i = 0; i < (size - 1); i++)
{
    cout << list[i] << endl;
}

//Adding an index

cout << "\nNow, please enter the index position to add to: " << endl;
cin >> addIndex;
cout << "\nEnter the number to add to the index: " << endl;
cin >> newInt;

for (i = size - 1; i >= addIndex - 1; i--)
{
    list[i + 1] = list[i];
}
        list[addIndex - 1] = newInt;
        size++;

    cout << "The number has been added at the specified index position." << 
endl;
    cout << "The new array is: " << endl;
    for (i = 0; i < size; i++)
    {
        cout << list[i] << endl;
    }



    return 0;
}

Answer 1

问题在于在您的代码中处理 size 变量。

以下是更正的代码。看到它工作here：

#include <iostream>
using namespace std;

const int CAP = 10;

int main()
{
    int size;
    int list[CAP] = { 12, 34, 45, 2, 8, 10, 16, 180, 182, 22 };
    size = CAP;
    int i, delIndex, addIndex, newInt = 0;

    cout << "Your list is: " << endl;
    for (i = 0; i < size; i++)
    {
        cout << list[i] << endl;
    } 

    //Deleting an index

    cout << "\nPlease enter index to delete from: ";
    cin >> delIndex;

    for (i = delIndex; i < size; i++)
    {
        list[i] = list[i + 1];
    }
    size--;
    cout << "The index position you specified has been deleted." << endl;
    cout << "The new array is: " << endl;
    for (i = 0; i < size; i++)
    {
        cout << list[i] << endl;
    }

    //Adding an index

    cout << "\nNow, please enter the index position to add to: " << endl;
    cin >> addIndex;
    cout << "\nEnter the number to add to the index: " << endl;
    cin >> newInt;

    for (i = size - 1; i >= addIndex; i--)
    {
        list[i + 1] = list[i];
    }
    list[addIndex] = newInt;
    size++;

    cout << "The number has been added at the specified index position." <<endl;
    cout << "The new array is: " << endl;
    for (i = 0; i < size; i++)
    {
        cout << list[i] << endl;
    }
    return 0;
}

注意：由于我们说的是数组中的index而不是position，所以它被视为0 based and element被添加到 index addIndex，而不是 addIndex-1。

Answer 2

你的程序有一些漏洞，你可以改进。

1. 您正在声明一个常量 (CAP)，但数组大小正在发生变化，因此请务必这样做。

2. 您正在多次打印数组，最好使用一个函数，并在每次需要打印整个数组时调用它。

3. 您在程序的某些部分使用了像 10 这样的文字。建议使用 size 或 CAP 等相同的变量而不是 10 以提高可读性。

4. 您甚至可以将插入和删除放在函数中，以便可以多次调用它们。

这是一个示例工作代码，您可以理解它。我还没有实施第 4 步，希望你能轻松完成，

LIVE CODE

工作代码

//This program demos basic arrays
#include <iostream>
using namespace std;
int CAP = 10;

void printArr(int list[]){
    for (int i = 0; i < CAP; i++)
        cout << list[i] << " ";
    cout<<endl;
}

int main()
{
    int list[CAP] = { 12, 34, 45, 2, 8, 10, 16, 180, 182, 22 };
    int i, delIndex, addIndex, newInt = 0;
    cout << "Your list is: " << endl;
    printArr(list);

    //Deleting an index
    cout << "\nPlease enter index(0 indexed based) to delete from: ";
    cin >> delIndex;
    for (i = delIndex; i < CAP - 1; i++)
        list[i] = list[i + 1];
    CAP--;
    cout << "The index position you specified has been deleted." << endl;
    cout << "The new array is: " << endl;
    printArr(list);

    //Adding an index
    cout << "\nNow, please enter the index position(0 indexed based) to add to: " << endl;
    cin >> addIndex;
    cout << "\nEnter the number to add to the index: " << endl;
    cin >> newInt;
    for (i = CAP; i > addIndex; i--)
        list[i] = list[i-1];        
    list[addIndex] = newInt;
    CAP++;
    cout << "The number has been added at the specified index position." << endl;
    cout << "The new array is: " << endl;
    printArr(list);
    return 0;
}