CC150 17.9

17_9.cpp

/* CC150 17.9 */
// find the frequency of occurrences of any given word in a book

#include <iostream>
#include <string>
#include <unordered_map>
#include <fstream>

using namespace std;

// single query: go through the book to count the occurrences

// multiple query: pre-processing, create a freq hash table
// assume case sensitive
// pre-processor read directly from file
unordered_map<string, int> wordFreqCount(string filename)
{
	ifstream fin(filename);
	string word;
	unordered_map<string, int> wordFreq;
	while (fin >> word) {
		if (wordFreq.find(word) == wordFreq.end())
			wordFreq[word] = 1;
		else
			++wordFreq[word];
	}
	fin.close();
	return wordFreq;
}

int main()
{
	string filename = "book.txt";
	unordered_map<string, int> wordFreq = wordFreqCount(filename);
	string word;
	cout << "Enter a word to count: ";
	cin >> word;
	if (wordFreq.find(word) != wordFreq.end())
		cout << wordFreq[word] << endl;
	else
		cout << "Not found!" << endl;
	return 0;
}