lab 3.1 c++

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

using namespace std;

int choiceCheck() {
    int choice;
    bool isIncorrect;
    do {
        isIncorrect = true;
        cin >> choice;
        if (cin.fail() || (cin.get() != '\n')) {
            cout << "Error! Input a number" << endl;
            cin.clear();
            while (cin.get() != '\n');
        } else {
            cin.clear();
            if (choice > 0 && choice < 3) {
                isIncorrect = false;
            } else {
                cout << "Error! Input 1 or 2" << endl;
            }
        }

    } while (isIncorrect);
    return choice;
}

string checkInputFilePath() {
    string path;
    bool isInCorrect;
    do {
        cout << "Input path to the file:\n";
        isInCorrect = false;
        cin >> path;
        ifstream fin(path);
        if (!fin.is_open()) {
            cout << "Could not open the file" << endl;
            isInCorrect = true;
        } else {
            fin.close();
        }

    } while (isInCorrect);
    return path;
}

string inputCheck() {
    bool isIncorrect;
    string str;
    int i;
    do {
        cout
                << "Input the string consisting of numbers, letters of the English alphabet and symbols '-', '+', '.' "
                << endl;
        isIncorrect = false;
        cin >> str;
        for (i = 0; i < str.length(); i++) {
            if (!(str[i] == 43 || str[i] == 45 || str[i] == 46 || (str[i] > 47 && str[i] < 58) ||
                  (str[i] > 64 && str[i] < 91) || (str[i] > 96 && str[i] < 123))) {
                cout << "Incorrect string format\n";
                isIncorrect = true;
            }
        }
    } while (isIncorrect);
    return str;
}

string fileCheckString() {
    string path, str;
    bool isIncorrect;
    int i;
    do {
        path = checkInputFilePath();
        ifstream fin(path);
        isIncorrect = false;
        fin >> str;
        if (fin.fail()) {
            cout << "The data is incorrect" << endl;
            isIncorrect = true;
        }
        if (!isIncorrect && (str.length() < 1)) {
            cout << "The string is empty" << endl;
            isIncorrect = true;
        }
        if (!fin.eof()) {
            cout << "There should be only one string" << endl;
            isIncorrect = true;
        }
        if (!isIncorrect) {
            for (i = 0; i < str.length(); i++) {
                if (!((str[i] == 43 || str[i] == 45 || str[i] == 46 || (str[i] > 47 && str[i] < 58) ||
                       (str[i] > 64 && str[i] < 91) || (str[i] > 96 && str[i] < 123)))) {
                    isIncorrect = true;
                }
            }
        }
        if (isIncorrect) {
            cout << "Incorrect string format" << endl;
        }
        fin.close();
    } while (isIncorrect);
    return str;
}

string inputChoice() {
    int choice;
    string str;
    cout << "Choose input option:\n1.Input through console\n2.Input through file" << endl;
    choice = choiceCheck();
    if (choice == 1) {
        str = inputCheck();
    } else {
        str = fileCheckString();
    }
    return str;
}

string checkOutputFilePath() {
    string path;
    bool isIncorrect;
    cout
            << "Input file path and the name of the file for\nexample C:\\Projects\\Number\\FileName.txt. If the\nfile does not exist, then it will be created\nautomatically in the root folder of the program:\n";
    isIncorrect = false;
    cin >> path;
    ifstream fin(path);
    if (!fin.is_open()) {
        cout << "Could not open the file or it does not exist" << endl;
        isIncorrect = true;
    } else {
        fin.close();
    }
    if (isIncorrect) {
        cout << "File will be created in the root folder of the program\n";
        path = "Result.txt";
    }
    return path;
}

void findConsoleSubStr(string str) {
    string subStr;
    int i;
    bool isFound;
    isFound = false;
    subStr = "";
    for (i = 0; i < str.length(); i++) {
        if (str[i] == '+' || str[i] == '-') {
            if (subStr.length() > 1) {
                cout << subStr << endl;
            } else {
                if (i>1) && (str[i - 1] == '0') {
                    cout << "0" << endl;
                }
            }
            subStr = "";
            subStr += str[i];
            isFound = true;
        } else {
            if (str[i] == 46 || (str[i] > 64 && str[i] < 91) || (str[i] > 96 && str[i] < 123)) {
                isFound = false;
                if (subStr.length() > 1) {
                    cout << subStr << endl;
                } else {
                    if (i>1) && (str[i - 1] == '0') {
                        cout << "0" << endl;
                    }
                }
                subStr = "";
            } else {
                if (str[i] == 48) {
                    if (isFound && !(subStr[subStr.length() - 1] == '+' || subStr[subStr.length() - 1] == '-')) {
                        subStr += str[i];
                    }
                } else {
                    if (str[i] > 48 && str[i] < 58) {
                        if (isFound) {
                            subStr += str[i];
                        }
                    }
                }
            }
        }
    }
    if (isFound && subStr.length() > 1) {
        cout << subStr << endl;
    }
}

void findFileSubStr(string str) {
    string subStr, path;
    int i;
    bool isFound;
    isFound = false;
    subStr = "";
    path = checkOutputFilePath();
    ofstream fout(path);
    subStr = "";
    for (i = 0; i < str.length(); i++) {
        if (str[i] == '+' || str[i] == '-') {
            if (subStr.length() > 1) {
                fout << subStr << endl;
            } else {
                if (i>1) && (str[i - 1] == '0') {
                    fout << "0" << endl;
                }
            }
            subStr = "";
            subStr += str[i];
            isFound = true;
        } else {
            if (str[i] == 46 || (str[i] > 64 && str[i] < 91) || (str[i] > 96 && str[i] < 123)) {
                isFound = false;
                if (subStr.length() > 1) {
                    fout << subStr << endl;
                } else {
                    if (i>1) && (str[i - 1] == '0') {
                        fout << "0" << endl;
                    }
                }
                subStr = "";
            } else {
                if (str[i] == 48) {
                    if (isFound && !(subStr[subStr.length() - 1] == '+' || subStr[subStr.length() - 1] == '-')) {
                        subStr += str[i];
                    }
                } else {
                    if (str[i] > 48 && str[i] < 58) {
                        if (isFound) {
                            subStr += str[i];
                        }
                    }
                }
            }
        }
    }
    if (isFound && subStr.length() > 1) {
        fout << subStr << endl;
    }
    cout << "Successful output\n";
}

void outputChoice(string str) {
    int choice;
    cout << "Choose output option:\n1.Output through console\n2.Output through file" << endl;
    choice = choiceCheck();
    if (choice == 1) {
        findConsoleSubStr(str);
    } else {
        findFileSubStr(str);
    }
}

int main() {
    string str;
    str = inputChoice();
    outputChoice(str);
    return 0;
};