Simple Dictionary console program.

Dictionary.cpp

/*
Warning: The following application was written in ISO C++11 standard, so it may incompatible with older C++ standards
Compiled by GCC with -std=c++11 flag
*/
#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib> // for using rand() and srand()
#include <ctime> // for using time()
 
using namespace std;
 
#define FPATH "Dictionary.txt" // file path
 
struct Word {
    string English;
    string Vietnamese;
    string Type;
};
 
void quicksort(Word [], const int, const int); // sort by English attribute of Word
int binsearch(const Word [], const int, const int, const string); // search for position of string kstr in Word array, by English attribute
string formalize(const string); // make the string to compatible with Dictionary database's format
 
int main() {
    int n = 0;
    Word *arr = nullptr; // nullptr represent for NULL pointer, which is a new feature in C++11 standard
    string tstr;
    // read and store database in Word array
    ifstream f(FPATH);
    if (!f) { // error handle
        cout << "Error on loading database! Process terminated.\n";
        return -1;
    }
    while (!(f >> ws).eof()) { // count the number of lines in the file - in a safety way
    	getline(f, tstr);
    	if (f.fail()) {
			break;
		}
        n++;
    }
    n /= 3;
    arr = new Word[n]; // allocating an array of Word which has n members
    f.seekg(f.beg); // return the buffer to the beginning of the file
    for (int i = 0; i < n; i++) { // actually read each Word from the begin to the end of the file
        getline(f, tstr);
        arr[i].English = formalize(tstr);
        getline(f, arr[i].Vietnamese);
        getline(f, arr[i].Type);
    }
    f.close();
    // sort Word array by Quick Sort algorithm and by English attribute
    srand((unsigned int)time(nullptr)); // create a random seed
    quicksort(arr, 0, n - 1);
    // user interface
    cout << "List of " << n << " English words available in Dictionary database (sorted):\n";
    for (int i = 0; i < n; i++) {
        cout << "- " << arr[i].English << '\n';
    }
    cout << '\n';
    do {
        cout << "Enter an English word to search for its meaning in Vietnamese and type: ";
        getline(cin, tstr);
        tstr = formalize(tstr);
        int k = binsearch(arr, 0, n - 1, tstr);
        if (k == -1) {
            cout << "Unable to find this English word in the Dictionary database!\n";
        }
        else {
            cout << "Here is it:\n";
            cout << "- English word:       " << arr[k].English << '\n';
            cout << "- Vietnamese meaning: " << arr[k].Vietnamese << '\n';
            cout << "- Type of the word:   " << arr[k].Type << '\n';
        }
        cout << "Continue? (Y/N): ";
        getline(cin, tstr);
        tstr = formalize(tstr);
    } while (!(tstr.size() == 1 && tstr[0] == 'n')); // the program exit only if user enter 'n' or 'N'
    // clean up garbages and exit application
    delete[] arr;
    arr = nullptr;
    return 0;
}
 
void quicksort(Word arr[], const int l, const int r) {
    if (l >= r) {
        return;
    }
    string p = arr[l + rand() % (r - l + 1)].English;
    int i = l, j = r;
    do {
        while (arr[i].English < p) {
            i++;
        }
        while (arr[j].English > p) {
            j--;
        }
        if (i <= j) {
            if (i < j) {
                Word t = arr[i];
                arr[i] = arr[j];
                arr[j] = t;
            }
            i++;
            j--;
        }
    } while (i <= j);
    quicksort(arr, l, j);
    quicksort(arr, i, r);
}
int binsearch(const Word arr[], const int l, const int r, const string kstr) {
    if (r == -1 || (l == r && kstr != arr[l].English)) {
        return -1;
    }
    int mid = l + (r - l) / 2;
    if (kstr == arr[mid].English) {
        return mid;
    }
    if (kstr > arr[mid].English) {
        return binsearch(arr, mid + 1, r, kstr);
    }
    else {
        return binsearch(arr, l, mid - 1, kstr);
    }
}
string formalize(const string str) {
    string tstr = str;
    int n = tstr.size();
    // normalize all letters in tstr
    for (int i = 0; i < n; i++) {
        if (tstr[i] > 'A' && tstr[i] < 'Z')
            tstr[i] += 32;
    }
    // truncating spaces at the end of tstr
    int i = n - 1;
    while (tstr[i] == ' ') {
        i--;
    }
    tstr.resize(i + 1);
    return tstr;
}