laba_3_2_c++

#include <iostream>
#include <fstream>
#include <set>

using namespace std;
ifstream fin;
ofstream fout;

bool choose() {
    int inputNumber;
    bool isIncorrect;
    const int MIN_NUM = 0;
    const int MAX_NUM = 1;
    do {
        cin >> inputNumber;
        isIncorrect = false;
        if (cin.fail()) {
            isIncorrect = true;
            cout << "Please, enter a number." << endl;
            cin.clear();
            while (cin.get() != '\n');
        }
        if (!isIncorrect && (inputNumber < MIN_NUM || inputNumber > MAX_NUM)) {
            cout << "You are out of input range!" << endl;
            isIncorrect = true;
        }
    } while (isIncorrect);
    if (inputNumber == 1)
        return true;
    else
        return false;
}

string inputFilePath() {
    const int EXTENSION_SIZE = 4;
    string path;
    string ext;
    bool isIncorrect;
    do {
        isIncorrect = false;
        cout << "Input path to file: " << endl;
        cin >> path;
        fin.open(path);
        if (path.size() > EXTENSION_SIZE) {
            ext = path.substr(path.size() - EXTENSION_SIZE, EXTENSION_SIZE);
        }
        else {
            cout << "Incorrect file name." << endl;
            isIncorrect = true;
        } if (!isIncorrect && ext != ".txt") {
            cout << "Must have .txt!" << endl;
            isIncorrect = true;
        }
        else if (!isIncorrect && !fin.is_open()) {
            cout << "Wrong way to file." << endl;
            isIncorrect = true;
        }
    } while (isIncorrect);
    fin.close();
    return path;
}

string inputSequence(){
    string sequence;
    cout << "Input Sequence" << endl;
    cin >> sequence;
    return sequence;
}

string inputSequenceFromFile(string path) {
    string sequence;
    fin.open(path);
    fin >> sequence;
    return sequence;
}

void fileOutput(set <char> setOfSymbols) {
    set <char>::iterator output;
    string path = inputFilePath();
    fout.open(path);
    if (setOfSymbols.empty())
        fout << "You have not entered any signs of arithmetic operations or digits.";
    else{
        fout << "The resulting set" << endl;
        for (output = setOfSymbols.begin(); output != setOfSymbols.end(); ++output)
            fout << *output << " ";
    }
    cout << "Successful output in file." << endl;
    fout.close();
}

void consoleOutput(set <char> setOfSymbols) {
    set <char>::iterator output;
    if (setOfSymbols.empty())
        cout << "You have not entered any signs of arithmetic operations or digits." << endl;
    else{
        cout << "The resulting set" << endl;
        for (output = setOfSymbols.begin(); output != setOfSymbols.end(); ++output)
            cout << *output << " ";
    }

}

set <char> makeSet(string sequence){
    set <char> setOfSymbols{};
    set <char> symbols{ '/', '*', '-', '+', '%', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
    for (int i = 0; i < size(sequence); i++){
        if (symbols.count(sequence[i]) == 1)
            setOfSymbols.insert(sequence[i]);
    }
    return setOfSymbols;
}

int main() {
    cout << "Given a non-empty sequence of characters, it is required to construct and print a set whose elements are signs of arithmetic operations and digits that occur in the sequence." << endl;
    string sequence;
    set <char> setOfSymbols{};
    cout << "Type 1 - console input, type 0 - file input." << endl;
    bool choice = choose();
    if (choice)
        sequence = inputSequence();
    else
    {
        string path = inputFilePath();
        sequence = inputSequenceFromFile(path);
    }

    setOfSymbols = makeSet(sequence);

    cout << "Type 1 - console output, type 0 - file output." << endl;
    choice = choose();
    if (choice)
        consoleOutput(setOfSymbols);
    else
        fileOutput(setOfSymbols);
    return 0;
}