Re: Function to output words in a vector and the occurrence.

"Jim Langston" <>
Thu, 19 Apr 2007 16:53:13 -0700
"Xernoth" <> wrote in message


I have an exercise that requests the following:

Write a function that reads words from an input stream and stores them
in a vector.
Use that function both to write programs that count the number of
words in the input,
and to count how many times each word occurred.

The below code works fine, but would like some advice on the
occurrence count.

I have commented out the part that concerns me.

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

using std::cin;
using std::cout;
using std::endl;
using std::istream;
using std::string;
using std::vector;

istream& read(istream& in, vector<string>& words)
   if (in)
       string temp;
       while (in >> temp)

   return in;

int main()
   cout << "Enter a list of words:" << endl;

   vector<string> words;
   read(cin, words);

   vector<string>::size_type vecSize = words.size();

   cout << "You entered " << vecSize << " words." << endl;

   for (vector<string>::size_type i = 0; i < vecSize; i++)
       int wordCount = 0;
       for (vector<string>::size_type j = 0; j < vecSize; j++)
           if (words[i] == words[j])
               wordCount += 1;
               //if (wordCount > 1)
               // words.erase(words.begin() + j);
               // vecSize = words.size();
       cout << "The word: " << words[i] << " occured " << wordCount
<< " times." << endl;

return 0;

With that portion of code commented, let's say I have an input with
the words:

"This that then that"

My output will appear as:

You entered 4 words.
The word: this occured 1 times.
The word: that occured 2 times.
The word: then occured 1 times.
The word: that occured 2 times.

With the code uncommented, the output appears as:
You entered 4 words.
The word: this occured 1 times.
The word: that occured 2 times.
The word: then occured 1 times.

Which is what I am after, but is commented code a poor method to
achieve this effect?

I have done a search and made a note of some responses using a
container of <string, int>, but the book I am following has not
covered this aspect.
Also I am aware of the use of size_t over ::size_type, but the book
has it's own method and am using that for the time being. It has also
not covered the use of ::iterator just yet.

Any advice is appreciated.

Well, you didn't specify what tools you were allowed to use. If you are
allowed to use std::map it becomes extremely easy. Consider.

std::map<std::string, int> WordCount;
// for loop

This one line of code does a whole bunch of things. You can add an entry to
a map by specifing a key that doesn't already exist in []. Then it would
increment it. A map has it's data part (.second) default constructued, for
an int it means it would be 0.

So... if WordCount[words[i]] doesn't exist, it adds it to the map, makes the
int 0, then increments it becuase of the ++ post increment.
If it already exists, it simply increments it.

When you are done iteratring through your words, you have a map keyed by the
word where the value is the number of times it appeared.

Iterate through the map when you are done to dispaly the values.

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