Re: Program to find occurences of a word in a file

From:

terminator <farid.mehrabi@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Thu, 22 Nov 2007 00:53:04 -0800 (PST)

Message-ID:

<cdb97a26-d1ee-425c-a557-a83a37de104a@s8g2000prg.googlegroups.com>

On Nov 20, 3:23 pm, Kai-Uwe Bux <jkherci...@gmx.net> wrote:

terminator wrote:

On Nov 20, 7:42 am, Kai-Uwe Bux <jkherci...@gmx.net> wrote:

Neehar wrote:

Hello
For one of the interviews I took recently, I was given an offline
programming quiz.
In 30 minutes I had to write code in C++ to counts the number of times
each unique word appears in a given file.
I tried my level best even after the quiz to come up with a solution
but cudnt find an efficient one. :(

This is what I did.

1. Read all the words from the file and store them in a vector
container.
2. Sort the words in the vector container using most efficient
algorithm ( like Quicksort, Mergesort etc)
3. Then finding duplicates and occurences is very easy.

I was asked to do this without sorting.
Is there a better way to do this?

  std::map< std::string, unsigned long > count;
  std::string word;
  while ( std::cin >> word ) {
    ++ count[ word ];
  }

Now, there are issues on deciding what a word is. The above just leaves
that to operator>>.

does map initialize values to zero for intrinsic types?

[23.3.1.2/1]:

T& operator[](const key_type& x);
Returns: (*((insert(make_pair(x, T()))).first)).second.

Note that the default-value is T(). For unsigned long, that would be 0.

plz check this to get surprised:

#include <iostream>
#include <conio.h>//a dos header
using namespace std;

template <typename T> struct testd{
    T t;
    testd():t(){};
};

int main(){
    testd<long> tl, *ptr=new testd<long> ;
    cout << tl.t << endl;
    cout << ptr->t << endl;
    delete ptr;
    getch();/*prevent the console from closing before viewing the
output*/
    return 0;
};

regards,
FM.