Question

我是C ++的新手（从我的代码中可以看出）我正在使用指针和数组以及我的结构练习动态内存分配。我的代码工作正常，直到它访问＆＃34; growArray＆＃34;函数，然后它给我SIGSEGV错误。我无法弄清楚为什么，因为据我所知，我正确地将指针传递给指针，并且我还为新指针分配空间。是我的结构的问题，还是传递指针的问题，还是接收指针的问题？我希望这个问题有道理。

#include <iostream>
#include <string>

using namespace std;

struct FriendInfo
{
  string name;
  string address;
  string number;
};

FriendInfo *growArray(FriendInfo *p_entry, int *size);

int main()
{
    int curNum = 0;
    int size = 2;
    int userAnswer;
    FriendInfo *p_friends = new FriendInfo[size];

    cout << "Enter a friend's info?(1 for yes, 0 for no)\n";
    cin  >> userAnswer;
    while (userAnswer != 0)
    {
        if (curNum == size)
        {
            p_friends = growArray (p_friends, &size);
        }
        cout << "What is your friend's name?\n";
        cin  >> p_friends[curNum].name;
        cout << "What is your friend's address?\n";
        cin  >> p_friends[curNum].address;
        cout << "What is your friend's number?\n";
        cin  >> p_friends[curNum].number;
        curNum++;
        cout << "Enter another friend? (1 for yes, 0 for no)\n";
        cin  >> userAnswer;
    }
}

FriendInfo *growArray(FriendInfo *p_entry, int *size)
{
    *size *= 2;
    FriendInfo *p_new_friends = new FriendInfo[*size];
    for (int i = 0; i < *size; ++i)
    {
        p_new_friends[i] = p_entry[i];
    }
    delete [] p_entry;
    return p_new_friends;
}

Answer 1

您的问题是，即使size属于p_entry，size的价值也会增加一倍。将代码更新为：

FriendInfo *growArray(FriendInfo *p_entry, int *size)
{
    int newSize = *size * 2;
    FriendInfo *p_new_friends = new FriendInfo[newSize];
    for (int i = 0; i < *size; ++i)
    {
        p_new_friends[i] = p_entry[i];
    }
    delete [] p_entry;
    *size = newSize;
    return p_new_friends;
}

Answer 2

在你的for循环中，你想在达到p_entry的大小后停止，而不是大小

FriendInfo *growArray(FriendInfo *p_entry, int *size)
{
    int orig_size = *size;
    *size *= 2;
    FriendInfo *p_new_friends = new FriendInfo[*size];
    for (int i = 0; i < orig_size; ++i)
    {
        p_new_friends[i] = p_entry[i];
    }
    delete [] p_entry;
    return p_new_friends;
}

SIGSEGV，分段错误

2 个答案: