动态数组大小和在getline（）崩溃；

Question

I've been working on a program recently that takes names as inputs and will eventually sort & binary search them. However upon attempting to make the array a dynamic size (that would increase by one with each loop iteration), it ran into various issues.

I can make the string array composed of 20 elements and the program works, but the extra credit for my assignment is to make it a dynamic size. Currently the program crashes without any sort of error code once it reaches "getline(cin, Names[x]);". I've been searching around and I know it'd be easier to do a vector instead of an array in this case, however I don't believe I'm allowed to use vectors on this assignment.

Thanks

Original Code

using namespace std;
#include <iostream>
#include <string>

void main()
{
    int x = 0;
    string * Names = new string[x];
    bool NameInputEnd(0);

    cout << "    Enter your names to be sorted\n";
    cout << "To exit just press [Enter] at any time\n";

    do
    {
        cout << x << endl;
        cout << "\n< Name " << (x + 1) << " > = ";

        !!**CRASHES HERE**!!

        getline(cin, Names[x]);

        if (Names[x].empty() || x == 19)
        {
            cout << "\nFinal Name Amount = " << (x + 1) << endl << endl;
            NameInputEnd = 1;
            continue;
        }

        x++;

    } while (NameInputEnd == 0);

    delete [] Names;
}

Changes

int tempsize(1), x(0);
string * Names = new string[tempsize];
...

do
{
...
    x++;
    tempsize++;
}while (NameInputEnd == 0);

Answer 1

An array cannot be resized once it has been created. You have to destroy it and create a new array with a copy of the existing data. For example:

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

void main()
{
    int x = 0;
    int capacity = 20;
    string * Names = new string[capacity];
    string Name;

    cout << "    Enter your names to be sorted\n";
    cout << "To exit just press [Enter] at any time\n";

    do
    {
        cout << x << endl;
        cout << "\n< Name " << (x + 1) << " > = ";

        if ((!getline(cin, Name)) || Name.empty())
            break;

        if (x == capacity)
        {
            int newCapacity = capacity + 20;
            string *newNames = new string[newCapacity];
            copy(Names, Names + x, newNames);
            delete [] Names;
            Names = newNames;
            capacity = newCapacity;
        }

        Names[x] = Name;
        ++x;    
    }
    while (true);

    cout << "\nFinal Name Amount = " << x << endl << endl;

    delete [] Names;
}

You really should use a std::vector , though:

#include <iostream>
#include <string>
#include <vector>

using namespace std;

void main()
{
    vector<string> Names;
    string Name;

    Names.reserve(20); // optional

    cout << "    Enter your names to be sorted\n";
    cout << "To exit just press [Enter] at any time\n";

    do
    {
        cout << Names.size() << endl;
        cout << "\n< Name " << (Names.size() + 1) << " > = ";

        if ((!getline(cin, Name)) || Name.empty())
            break;

        Names.push_back(Name);
    }
    while (true);

    cout << "\nFinal Name Amount = " << Names.size() << endl << endl;
}