c++ - 由于 while 循环中的条件而导致段错误

Question

我用字符串数组制作哈希表，在我的插入中，我有一个 while 语句，用于处理冲突和环绕。我玩过它，似乎只在使用条件语句时出现段错误 11。这是我的 while 循环:

while (numElm != length)
{
    numProbes = 0;
    int index = hash( newGuest );
    //handles collision and wraparound
    while (hashArray[index] != " " && hashArray[index] != "-1")
    {
        ++index;
        index %= length;
        numProbes = numProbes + 1;
    }

    //sets the array at the index eqaul to data
    hashArray[index] = newGuest;
    cout << newGuest << " has been inserted at index: " << index << " using " << numProbes << " probes";
    break;

}

当第二个 while 循环以两个条件语句开始时，就会出现问题。谁能告诉我为什么会这样？

编辑程序的其余部分

#include <cassert>
#include <iostream>
#include <cstdlib>
#include <stdlib.h>
#include <string>
#include "HashTable.h"

using namespace std;

//typedef double value_type;


HashTable::HashTable( int tableLength )
{   
    tableLength = 114;
    string *hashArray = new string[tableLength];
    length = tableLength;
    numElm = 0;

    for(int i = 0; i < length; i++)
    {
        hashArray[i] = " ";
    }
}


// Returns an array location for a given item key.
int HashTable::hash( string itemKey )
{
    int value = 0;
    for (int i = 0; i < itemKey.size(); i++ )
    {
        value += itemKey[i];
    }
    return (value * itemKey.length() ) % length;
}

// Adds an item to the Hash Table.
void HashTable::insertGuest( string newGuest )
{
//  int index = hash( newGuest );   
    //hashArray[ index ].insertGuest( newGuest );
//  cout << newGuest << " has been inserted at index: " << index;

//  string s = " ";
    while (numElm != length)
    {
        numProbes = 0;
        int index = hash( newGuest );
        //handles collision and wraparound
        while (hashArray[index] != " " && hashArray[index] != "-1")
        {
            ++index;
            index %= length;
            numProbes = numProbes + 1;
        }

        //sets the array at the index eqaul to data
        hashArray[index] = newGuest;
        cout << newGuest << " has been inserted at index: " << index << " using " << numProbes << " probes";
        break;

    }
}

// De-allocates all memory used for the Hash Table.
HashTable::~HashTable()
{
    delete [] hashArray;
}
//#endif

Answer 1

您不初始化您的成员 变量hashArray，只在您的构造函数中初始化一个本地 变量hashArray。您类中的 hashArray 保持未初始化状态，并在使用时导致崩溃。要修复，更换

string *hashArray = new string[tableLength];

与

hashArray = new string[tableLength];

这解决了问题。否则代码有很多风格和代码方面的问题，但我希望你能继续学习自己解决这些问题。祝你好运!