连续字符串输入的C 动态数组

Question

我需要在C 中进行动态数组，并要求用户输入名称，直到用户键入exit。

它应该不断要求越来越多的名称，将它们记录到动态字符串数组，然后随机选择与用户从列表中想要的名称一样多。

我应该能够弄清楚随机数部分，但是连续的输入给我带来了问题。我不确定如何使长度变量继续更改值。

#include <iostream>
#include <string>
using namespace std;
int main()
{
    int length;
    string* x;
    x = new string[length];
    string newName;
    for (int i = 0; i < length; i++)
    {
        cout << "Enter name: (or type exit to continue) " << flush;
        cin >> newName;
        while (newName != "exit")
        {
            newName = x[i];
        }
    }
    cout << x[1] << x[2];
    int qq;
    cin >> qq;
    return 0;
}

任何帮助将不胜感激。

Answer 1

一些错误：

1. length从未分配一个值
2. 您正在用newName = x[i];中的数组的未分配值x[i]覆盖newName
3. x从未用新的length
进行动态重新分配

让我们考虑一个解决方案：

#include <iostream>
#include <string>
using namespace std;
int main()
{
    int length = 2; // Assign a default value
    int i = 0;      // Our insertion point in the array
    string* x;
    x = new string[length];
    string newName;
    cout << "Enter name: (or type exit to continue) " << flush;
    cin >> newName; // Dear diary, this is my first input
    while (newName != "exit")
    {
        if (i >= length) // If the array is bursting at the seams
        {
            string* xx = new string[length * 2]; // Twice the size, twice the fun
            for (int ii = 0; ii < length; ii++)
            {
                xx[ii] = x[ii]; // Copy the names from the old array
            }
            delete [] x; // Delete the old array assigned with `new`
            x = xx;      // Point `x` to the new array
            length *= 2; // Update the array length
        }
        x[i] = newName; // Phew, finally we can insert
        i++;            // Increment insertion point
        cout << "Enter name: (or type exit to continue) " << flush;
        cin >> newName; // Ask for new input at the end so it's always checked
    }
    cout << x[1] << x[2]; // Print second and third names since array is 0-indexed
    int qq;
    cin >> qq; // Whatever sorcery this is
    return 0;
}

解决提到的错误：

1. length在开始时分配了默认值
2. 扭转获得x[i] = newName;的方向
3. x被动态分配了一个新数组的指数增压length

快乐学习！