Question

在那里，我是C ++的新手，我的问题很小。有一个名为＆＃34; bool checkIfPersonAlreadyExists（）{...}＆＃34;我希望这个函数返回一个bool类型的变量，但它没有。谁能帮我这个？（答案应该是＆＃34; true＆＃34;或＆＃34; false＆＃34;但是以这种形式：＆＃34;返回IfPersonAlreadyExists＆＃34;）。

#include <iostream>
#include <cctype>
#include <cstdlib>

using namespace std;

class Library {
    private:
        string name, surname;
        int LSP;
        bool IfPersonAlreadyExists;

        //toString metodas ir kaip ji pasiekti is private?????
        string toString (string name) {
            cout << name << " " << surname << " " << LSP << endl;
            return name;
        }
    public:
        //setters
        int setName (string name) {
            if (!name.empty() && isalpha(name[0]) && isupper(name[0]))
               this -> name = name;
            else {
                cout << "Wrong entry!" << endl;
                return 0;
            }
        }
        int setSurname (string surname) {
            if (!surname.empty() && isalpha(surname[0]) && isupper(surname[0]))
                this -> surname = surname;
            else {
                cout << "wrong entry!" << endl;
                return 0;
            }
        }
        int setLSP (int LSP) {
            if (LSP > 0)
                this -> LSP = LSP;
            else {
                cout << "Wrong entry!" << endl;
                return 0;
            }
        }
        void setIfPersonAlreadyExists (bool IfPersonAlreadyExists) {
            this -> IfPersonAlreadyExists = IfPersonAlreadyExists;
            IfPersonAlreadyExists = true;
        }
        //getters
        string getName () {
            return name;
        }
        string getSurname () {
            return surname;
        }
        int getLSP () {
            return LSP;
        }
        bool getIfPersonAlreadyExists () {
            return IfPersonAlreadyExists;
        }

        //Kaip padaryti kad return true or false?????/?
        bool checkIfPersonAlreadyExists (bool IfPersonAlreadyExists, int LSP) {
            int LSPCheck;
            cout << "Enter LSP number to check" << endl;
            cin >> LSPCheck;
            if (LSPCheck != LSP) {
                IfPersonAlreadyExists = false;
                //cout << boolalpha << IfPersonAlreadyExists << endl;
                return IfPersonAlreadyExists;
            }
            else {
                IfPersonAlreadyExists = true;
                cout << boolalpha << IfPersonAlreadyExists << endl;
                return IfPersonAlreadyExists;
            }
        }
};


int main () {
    Library library;
    string name, surname;
    int LSP;
    bool IfPersonAlreadyExists = true;
    cout << "Enter your name: " << endl;
    cin >> name;
    library.setName(name);
    //cout << library.getName() << endl;

    cout << "Enter your surname: " << endl;
    cin >> surname;
    library.setSurname(surname);
    //cout << library.getSurname() << endl;

    cout << "Enter your LSP number: " << endl;
    cin >> LSP;
    library.setLSP(LSP);
    //cout << library.getLSP() << endl;
    //library.toString(name);

    library.setIfPersonAlreadyExists(IfPersonAlreadyExists);
    // cout << library.getIfPersonAlreadyExists() << endl;

    library.checkIfPersonAlreadyExists(IfPersonAlreadyExists, LSP);

    return 0;
}

Answer 1

为了打印true和false而不是1和0分别使用std::boolalpha，如下例所示：

std::cout << std::boolalpha << library.checkIfPersonAlreadyExists(IfPersonAlreadyExists, LSP) << std::endl;

成员函数Library::checkIfPersonAlreadyExists已经返回bool。

编辑：

还包括string标题（即#include <string>）。

Answer 2

cout＆lt;＆lt; library.getIfPersonAlreadyExists（）＆lt;＆lt; ENDL;

我认为应该返回0或1。

只做cout＆lt;＆lt; （library.getIfPersonAlreadyExists（）== true？＆＃34; true＆＃34;：＆＃34; false＆＃34;）＆lt;＆lt; ENDL;

Answer 3

如果对本地化，全局变量和参数使用不同的大小写，您将会变得更加困惑。

    void setIfPersonAlreadyExists (bool IfPersonAlreadyExists) {
        this -> IfPersonAlreadyExists = IfPersonAlreadyExists;
        IfPersonAlreadyExists = true;
    }

总是如此！

C ++打印出bool类型变量

3 个答案: