Error calling functions

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Error calling functions

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#1 by (2 votes)
#2 by (1 votes)

0

The program consists of hitting the lottery and then hitting another prize.

The problem is when declaring the congratulations function (). When I call this from the main it gives me an error and if I call it at the end of the lottery () function, it does not run but it does not skip error.

#include <iostream>
#include <fstream>

using namespace std;

bool loteria();
void felicitaciones(bool premio,bool bonus);

int main()
{
    loteria();
    return 0;
}

bool loteria()
{
    int num,num2;
    bool premio,bonus;
    cout<<"Introduce un numero del 1 al 9:";
    cin >> num;

    if(num==8)
    {
        cout <<endl<< "Premio"<<endl;
        premio=true;
    }else
    {
        cout << "Nada";
        return 0;
    }

    cout << "Si acierta de nuevo se lleva un bonus:";
    cin >> num2;

     if(num2==1)
    {
        cout << endl<<"Bonus"<<endl;
        bonus=true;
        return premio,bonus;
    }else
    {
        cout << "Nada";
        bonus=false;
        return premio,bonus;
    }
    felicitaciones(premio,bonus);
}

void felicitaciones(bool premio, bool bonus)
{
    if(premio==true && bonus==true)
    {
        cout << "Usted es un afortunado";
    }
    else
    {
        cout << "No tiene mucha suerte";
    }
}

c++

asked by Vendetta 09.11.2017 в 13:33

source

2 answers

2

C ++ does not allow multiple return of values.

In your function loteria() you have returns like this:

return premio,bonus;

What that code does is invoke the comma operator ( , ) on premio and bonus . The comma operator evaluates the first expression ( premio ), discards it, and executes the second expression ( bonus ) and returns that expression. So your return order is exactly the same as:

return bonus;

Well, C ++ if you allow multiple return of values if you know how to do it.

Changing your function bool loteria() to std::pair<bool, bool> loteria() could return two values if your return statement is like this:

return {premio,bonus};
//     ^~~~~~~~~~~~~^ <-- construye un std::pair<bool, bool>

But it forces you to double the return on all points of the function, so your return 0; when you do not get a reward should be like this:

return {false,false};
//     ^~~~~~~~~~~~^ <-- construye un std::pair<bool, bool>

You can pick up the return of bool loteria() to C ++ 17 style:

int main()
{
    auto [premio, bonus] = loteria();
    return 0;
}

If your compiler does not yet support C ++ 17 you can pick up the return like this:

int main()
{
    auto estado = loteria();
    bool premio = estado.first, bonus = estado.second;
    return 0;
}

answered by 09.11.2017 в 14:17

I can not define multiple script tags SQL Server, inner joins

score 1 · Accepted Answer

Your code has some other fault:

You can not put that kind of double return , since it's only going to return a single thing. If you need to return more than one element, I advise you to use another type of structure, either a TAD , or one that is returned, and the other, a parameter passed by reference, etc.

It does not make sense that the lottery () function has return value, because in your case you do not use it.

The congratulations function is not executed because if you set the function * lottery * it has a return value if it fulfills the 2nd condition (num2==1) and if not, it will return the following statement else . Now, your code continues, but it does not make sense since you will not get to execute any sentence after the return statement.

Precisely at the syntactic and logical level the congratulations function is correct. One possible implementation is the following:

#include <iostream>
#include <fstream>

using namespace std;

void loteria(bool &premio, bool &bonus); // las variables son pasadas por referencia 
void felicitaciones(bool premio,bool bonus);

int main()
{
    bool premio = false;
     bool bonus = false;
    loteria(premio, bonus);
    felicitaciones (premio, bonus);
}

void loteria(bool &premio, bool &bonus)
{
    int num,num2;
    cout<<"Introduce un numero del 1 al 9:";
    cin >> num;

    if(num==8)
    {
        cout <<endl<< "Premio"<<endl;
        premio=true;
    }else
    {
        cout << "Nada";
    }

    cout << "Si acierta de nuevo se lleva un bonus:";
    cin >> num2;

     if(num2==1)
    {
        cout << endl<<"Bonus"<<endl;
        bonus=true;
    }else
    {
        cout << "Nada";
    }
}

void felicitaciones(bool premio, bool bonus)
{
    if(premio==true && bonus==true)
    {
        cout << "Usted es un afortunado";
    }
    else
    {
        cout << "No tiene mucha suerte";
    }
}