CODEWITHSUNDEEP
c++vectorindexoutofboundsexception
Tobias Nilsson
Tobias Nilsson

Reputation: 41

out of bound while iterating over vector

I am making a program that will take in a text and:

  1. count how many times a word is found
  2. save them into a struct
  3. print out how many times the words are found.

But I'm having a problem when I try to compare a string against a struct string member. I get vector out of range. Please review the code below. Hope someone can tell me what i am doing wrong 

#include <iostream>
#include<string>
#include <vector>

using namespace std;


struct word_entry {
  string word;
  int amount;
} ;

typedef vector<word_entry>  type_of_vector;

void insert(type_of_vector word_storage,string word_to_insert)
{
  bool word_found =false;

  for(int i = 0;i<=word_storage.size();i++)
    {
      if(word_storage.at(i).word==word_to_insert) //crashes the program
        {
          word_storage.at(i).amount++; 
           word_found=true;
        } 
    }    
}

int main()
 {
   type_of_vector word_vector;
   string word_to_insert="kalle";   
   word_entry insert_word={word_to_insert,1};  
   word_vector.insert(word_vector.end(),insert_word);   
   insert(word_vector,word_to_insert); 
 }

Upvotes: 1

Views: 112

Answers (3)

Vlad from Moscow
Vlad from Moscow

Reputation: 310990

This for statement

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

gives you the exception because index equal to szie() is invalid. The valid range for indexes is [0, size() - 1] provided that the vector is not empty.

Instead of the loop you could use standard algorithm std::find_if. For example

void insert(type_of_vector &word_storage, const string &word_to_insert)
{
   auto it = std::find_if( word_storage.begin(), word_storage.end(), 
                           [&]( const word_entry &entry ) { return ( entry.word == word_to_insert ); } );         
   if( it != word_storage.end() )
   {
       it->amount++;
   }
}

Upvotes: 0

marcinj
marcinj

Reputation: 49986

Few hints:

using namespace std;

dont include whole std namespace in your project

void insert(type_of_vector word_storage,string word_to_insert)

word_storage will always be a copy of what your have put in the function call, if you dont want a copy (and it looks like you dont) use reference type_of_vector& word_storage. Also it makes sense to use const string& word_to_insert, if word_to_insert is not supposed to change.

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

you are iterating out of bounds, use < compare rather than <=

Upvotes: 4

TobiMcNamobi
TobiMcNamobi

Reputation: 4813

It has to be

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

Use "less than" '<' instead of "less than or equal" '<='.

Upvotes: 5

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