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C++ program to print unique words in a file

  • Last Updated : 28 Jun, 2021

Write a function that takes a file name as argument and prints all unique words in it.

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The idea is to use map in STL to keep track of words already occurred.

// C++ program to print unique words in a string
#include <bits/stdc++.h>
using namespace std;
// Prints unique words in a file
void printUniquedWords(char filename[])
    // Open a file stream
    fstream fs(filename);
    // Create a map to store count of all words
    map<string, int> mp;
    // Keep reading words while there are words to read
    string word;
    while (fs >> word)
        // If this is first occurrence of word
        if (!mp.count(word))
            mp.insert(make_pair(word, 1));
    // Traverse map and print all words whose count
    //is 1
    for (map<string, int> :: iterator p = mp.begin();
         p != mp.end(); p++)
        if (p->second == 1)
            cout << p->first << endl;
// Driver program
int main()
    // Create a file for testing and write something in it
    char filename[] = "test.txt";
    ofstream fs(filename, ios::trunc);
    fs << "geeks for geeks quiz code geeks practice for qa";
    return 0;



Thanks to Utkarsh for suggesting above code.

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