为什么在执行main之前就出现分段错误（核心转储）？

Question

我有一个作业，必须使用完美的哈希来哈希输入数组中的名称，并给出名称的数量。

这是我的代码：

Dictionary.h

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

class Dictionary {
public:
    // Insert an input set of n keys to the dictionary. This method should print out the following information:
    // 1. The hash functions comprising the perfect hash (both levels)
    // 2. The sum of squares of the number of keys mapped to each bin of the first level hash function, and
    // 3. The number of trials needed to generate each hash function.
    void bulkInsert(int n, string *keys);

    // Insert a key to the dictionary.
    // Print out whether the insertion caused a collision in the second level hash.
    // Handle collision with separate chaining.
    void insert(string key);

    // Remove a key from the dictionary, if it exists.
    void remove(string key);

    // Return whether a key is found in the dictionary.
    // Print the buckets (both first and second level) accessed during the operation.
    bool find(string key);

    //make random matrix and print after
    void makeRandom(int nR, int nC);

    //format key and hash for first level, return index of hash
    int firstLevelHash(string input, int nR, int nC);

    //print hash
    void printHash();

private:
    vector<vector<int>> randomMat;
    vector<vector<int>> randomMat2;
    vector<vector<string>> hashTable;
};

Dictionary.cpp

#include "Dictionary.h"
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <cstdlib>
#include <time.h>
#include <vector>
#include <algorithm>
using namespace std;

void Dictionary::bulkInsert(int n, string *keys) {

        int numRow = (ceil(log2(n)));
        int numCol = 64;
        int trialNum = 1;
        bool repeat = true;
        while ( repeat ) {

                //make random matrix
                makeRandom(numRow, numCol);

                //check hashtable empty, clear if not
                if ( !( hashTable.empty() ) ) {
                        hashTable.clear();
                }

                //create hashtable, given by 2^numRow
                for ( int i = 0; i < ( 2^numRow ); i++ ) {
                        vector<string> row;
                        hashTable.push_back(row);
                }

                //loop through keys and hash first level
                for ( int i = 0; i<n; i++) {

                        int ind = firstLevelHash(keys[i], numRow, numCol);

                        hashTable[ind].push_back(keys[i]);
                }

                //check condition on whether to repeat hash
                int limit = 4*n;
                int summation = 0;
                for ( int i = 0; i < hashTable.size(); i++ ) {
                        summation = summation + ((hashTable[i].size())^2);
                }
                if ( summation < limit ) {
                        repeat = false;
                }

                //second level hashing
        }
}

void Dictionary::insert(string key) {

}
void Dictionary::remove(string key) {

}

bool Dictionary::find(string key) {

        return false;
}

//randomizes randomMat and prints;
void Dictionary::makeRandom(int nR, int nC) {
        vector<int> row;
        for ( int i = 0; i < nR; i++ ) {
               row.clear();
               for ( int j = 0; j < nC; j++ ) {
                       int random = rand()%2;
                       row.push_back(random);
               }
               randomMat.push_back(row);
        }


}

//returns vector for key of length 64
int Dictionary::firstLevelHash(string input, int nR, int nC) {

        //check length of input
        //if less than 8, add space to front
        if ( input.size() < 8 ) {
                for( int p = 0; p < 8-(input.size()); p++) {
                        input = " " + input;
                }
        }

        //obtain string of length 64 of bits of input
        string binStr = "";
        for ( char& chr : input) {
                binStr += bitset<8>(chr).to_string();
        }

        vector<int> keyVector;

        //go through string and convert each to bit
        for ( int i = 0; i < binStr.size(); i++ ) {
                string substr = binStr.substr(i, 1);
                int val = stoi(substr);
                keyVector.push_back( val );
        }

        vector<int> hashFinalValue;

        //multiply by hash
        for ( int j = 0; j < nR; j++ ) {
                int hashVal = 0;
                for ( int p = 0; p < nC; p++ ) {
                        hashVal = hashVal + (randomMat[j][p] * keyVector[p]);
                }
                hashVal = hashVal % 2;
                hashFinalValue.push_back( hashVal );
        }

        //convert binary to decimal to get index
        int index = 0;
        int q = 1;
        for ( int m = 0; m < hashFinalValue.size(); m++ ) {
                index += hashFinalValue[m] * ( 2^(hashFinalValue.size()-q) );
                q++;
        }

        return index;
}

//prints hashTable
void Dictionary::printHash() {

        for ( int i = 0; i < hashTable.size(); i++ ) {

                for ( int j = 0; j < hashTable[i].size(); j++ ) {
                        cout << hashTable[i][j];
                        cout << " | ";
                }

                cout << "\n";
        }

}

my_test_dictionary.cpp

#include "Dictionary.h"
#include <iostream>
using namespace std;

int main(){
        cout<<"adfad";
        Dictionary dict;

        string strs[] = {"Fred Astaire", "Lauren Bacall", "Brigitte Bardot", "John Belushi", "Ingmar Bergman"};
        int n = 5;

        dict.bulkInsert(n, strs);

        dict.printHash();

        return 0;
}

[当我使用g ++ Dictionary.cpp my_test_dictionary.cpp进行编译时，我立即收到“分段错误（核心已转储）”，并且main的第一行上的“ adfad”根本没有打印。

请帮助。我坏了。

Answer 1

您对到达main之前程序失败的断言为假。实际上，它在这里崩溃：