Filling An Array with Strings in C++

My aim is to fill an array of strings with each word in a dictionary file (/usr/share/dict/words). I'm able to iterate through each line in the file using an ifstream to determine the number of elements I will need in my string array. That being said, I am unclear how to instantiate and then fill my array of strings? I believe there is some casting I am missing, but nevertheless my code is below. Note the error occurs on line 40:

error: cannot convert 'std::string' to 'char*' for argument '1' to 'char* strncpy(char*, const char*, size_t)'

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fstream>
#include <sstream>
using namespace std;
const int MAX_WORD_LENGTH = 40;  

int main(int argc, char *argv[]){
    char c;

    int numLines = 0;
    string line;
    ifstream dictionary("/usr/share/dict/words");
    if (dictionary==0){      //exits program if dictionary file wasn't opened correctly
        fprintf(stderr, "failed to open /usr/share/dict/words\n");
        exit(1);
    }

    while (dictionary.get(c)){      //counts number of lines and stores them in int numLines
        if (c=='\n'){
            numLines++;
        }
    }
    //char *dictArray[numLines][MAX_WORD_LENGTH];
    string dictArray[numLines];
    printf("%d\n", numLines); //debugging
    for(int i = 0; i < numLines; i++){      //loop to fill string array with each word in dictionary file
        getline(dictionary, line);
        strncpy(dictArray[i], line.c_str(), 40);
    }   
}