Vector Subscript out of range error.The error occurs even if the vector has greater index than the index for which data is accessed

Question

I am using VC++ 2013.I'm trying to access the index of the vector where it shows vector subscript out of range.My code is given below:

std::string str="1,2,3, 4 , 0.00000 , ";
 vector<string>veclist;
 veclist=(tokenize(str,","));
 //Now the veclist has a size of 6.But when i am trying to access it through;
 long num=stol(veclist.at(4));

The code crashes and shows vector subscript out of range.I don't know why the code crashes and what's the error in this!!!

Answer 1

The code crashes and shows vector subscript out of range.I don't know why the code crashes and what's the error in this!!!

The message tells you all.

It crashes since you have no rights to access veclist.at(4) . Simply you have not enough elements in veclist or veclist is empty.

Check the number elements in veclist by veclist.size() after executing (tokenize(str,","));

Edit:

You may have different problem then reported. Your str tokens may not be liked by the stol function. That can cause the crash.

Consider this test program. I have written tokenize_split which should match yours.

#include <vector>
#include <string>
#include <string.h>
#include <sstream>
#include<iostream>

using namespace std;

std::vector<std::string> tokenize_split(const std::string &s, char delim) {
    std::stringstream ss(s);
    std::string item;
    std::vector<string> tokens;
    while (getline(ss, item, delim)) {
        tokens.push_back(item);
    }
    return tokens;
}

int main(void)
{
   std::string str1="1 2 3 4 5 6";
   std::string str2="1,2,3, 4 , 0.00000 , "; // Your string
   std::string str3="1,2,3,4,5,6";

   vector<string> veclist;
   long num; 

   veclist = tokenize_split(str3, ',');
   std::cout <<  "Size= " << veclist.size() << endl;
   std::cout <<  "Token= " << "<" << veclist.at(4) << ">"  << endl;
   num = std::stol(veclist.at(4));
   std::cout << "Number " << num  << endl << endl;

   veclist = tokenize_split(str2, ',');
   std::cout << "Size= " << veclist.size() << endl;
   std::cout <<  "Token= " << "<" << veclist.at(4) << ">"  << endl;
   num = std::stol(veclist.at(4));
   std::cout << "Number " << num  << endl << endl;

   veclist = tokenize_split(str1, ' ');
   std::cout <<  "Size= " << veclist.size() << endl;
   std::cout <<  "Token= " << "<" << veclist.at(4) << ">"  << endl;
   num = std::stol(veclist.at(4));
   std::cout << "Number " << num  << endl << endl;

   veclist = tokenize_split(str2, ' ');
   std::cout << "Size= " << veclist.size() << endl;
   std::cout <<  "Token= " << "<" << veclist.at(4) << ">"  << endl;
   num = std::stol(veclist.at(4));
   std::cout << "Number " << num  << endl;

   return 0;
}

Test:

Size= 6                                                                                                                                      
Token= <5>                                                                                                                                   
Number 5                                                                                                                                     

Size= 6                                                                                                                                      
Token= < 0.00000 >                                                                                                                           
Number 0

Size= 6                                                                                                                                        
Token= <5>                                                                                                                                     
Number 5                                                                                                                                       

Size= 5                                                                                                                                        
Token= <,>                                                                                                                                     
terminate called after throwing an instance of 'std::invalid_argument'                                                                         
  what():  stol                                                                                                                                
Aborted

Program crashes since your string str2 does not contain a valid number that could be successfully converted to long by the stol function. The token ',' will cause the abort.