简单聊天机器人的分段错误（核心转储）

Question

I'm having trouble with a simple chatbot. After I write 9 messages it says

Segmentation fault (core dumped)

My code is

#include <iostream>
#include <map>
#include <vector>
#include <string>
#include <ctime>

using namespace std;

const string user_template = "USER: ";
const string bot_template = "Bot: ";



int main(){

vector<string> Greeting{
    "Hi!",
    "Hey",
    "Hello",
    "What's up?",
    "What's good?"
};

vector<string> Responses{
    "Fine, thanks",
    "Good, thanks",
    "I'm OK",
    "Everything is good"
};
//srand((unsigned) time(NULL));

string sResponse = "";
string tResponse = "";

while(cin){
    string user_msg;
    cout << user_template;
    std::getline (std::cin, user_msg);
    int nSelection = rand() % 5;
    sResponse = Greeting[nSelection];
    tResponse = Responses[nSelection];
    if(user_msg == "quit"){
        break;
    }
    else if(user_msg == "How are you?"){
        cout << bot_template << tResponse << endl;
    }
    else{
        cout << bot_template << sResponse << endl;
    }
}
}

Picture of chatbot message

I want the messaging to continue indefinitely I've looked everywhere and can't find a solution to this problem. Any help would be appreciated.

Answer 1

You are getting outside the responses vector range. There are 4 responses, this means their indicies are in range from 0 to 3. rand() % 5 would return values in range from 0 to 4. When nSelection is equal to 4, you are trying to access element which is after the last in vector.

As a possible solution you can get response index like rand() % Responses.size() , then you will never get out of bounds. The situation when Responses is empty should be handled separately, to prevent dividing by zero.