添加输出文件后 C++ 代码无法正确编译

Question

我已经完成了大部分作业，这需要使用我目前已经正确启动并运行的三个函数。问题是当我添加相应的代码以输出到文件时，最后一个函数没有返回值并且我想要输出到文件的值没有写入文件。该过程也以返回 -1 结束。请查看下面的代码并告诉我我做错了什么。

#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

string* returnGreetings() {

    int const SIZE = 50000;
    string message;
    string* greetings = new string[SIZE];

    for (int i = 0; i < SIZE; i++)
    {

    if (i < 12500)
        {
            message = "Hi";
            greetings[i] = message;
        }
    else if (i >= 12500 && i < 25000)
        {
            message = "Hey";
            greetings[i] = message;
        }
    else if (i >= 25000 && i < 37500)
        {
            message = "Hello";
            greetings[i] = message;
        }
    else if (i >= 37500)
        {
            message = "What's up";
            greetings[i] = message;
        }
    }
    return greetings;
}

vector<string> returnVectorGreetings()
{
    string message;
    vector <string> greetings;

    for (int i = 0; i < 50000; i++)
    {

    if (i < 12500)
        {
            message = "Hi";
            greetings.push_back(message);
        }
    else if (i >= 12500 && i < 25000)
        {
            message = "Hey";
            greetings.push_back(message);
        }
    else if (i >= 25000 && i < 37500)
        {
            message = "Hello";
            greetings.push_back(message);
        }
    else if (i >= 37500)
        {
            message = "What's up";
            greetings.push_back(message);
        }
    }


    return greetings;
}

int addTen(int *numberAddress)
{
    return *numberAddress + 10;
}

int main()
{

    int *numberAddress;

    string* address = returnGreetings();

    cout << address;

    string *a = returnGreetings();

    for (int i = 0; i < 50000; i++) cout << a[i] << endl;

    vector<string> m = returnVectorGreetings();

    for (int i = 0; i < 50000; i++) cout << m[i] << endl;

    cout << "Please enter a number: ";

    cin >> *numberAddress;

    cout << "The number plus 10 is: " << addTen(numberAddress) << endl;

    ofstream outfile;
    outfile.open("output.txt");
    outfile << address;
    outfile.close();

    return 0;
}

Answer 1

就用这个 int *numberAddress = new int;

代替 int *numberAddress;

在使用该指针之前，您需要为该指针分配内存。