Question

I want to count word frequency from a article.

My thought is first create a struct array

 struct{
       char[WORD_SIZE]
 }data[MAX_WORD_NUMBER];

and then read each character then determine by

isalpha();

and then convert to lowercase by

tolower();

then store a word to each struct.

then make failure function for every word,

then test each word by call it.

1.But I don’t know how to count the frequency due to repetition has caused.

(I thought I can compare it each time when I read and insert a word, but it is so ineffective, is there a more efficient way?)

2.I think that my method call function too many time.

How can I use KMP more effectively?

Answer 1

You are programming in C or C++? You tagged your question with both.

Assuming you are using C++ then you are going to do much better with std::map to count your words. Something like this

#include <map>
#include <string>

std::map<std::string, int> data;

std::string word;

data[word] = 0; // set word count to zero
data[word]++; // increment word count

// print out all the word counts
for (std::map<std::string, int>::iterator i = data.begin();
  i != data.end(); ++i)
{
  cout << "word " << i->first << " occurs " << i->second << "times\n";
}

This task will be so much easier if you choose the right tools for the job. Of course if you are programming in C then none of this is going to help.