C++, getting i think the memory address instead of the string i want?

Question

I'm new to working on structures and came across this problem:

In Germany, the house number is displayed after the street name; for example, Bahnhofstraße 1. Change the print_address function from this section so that it can print addresses in either format.

#include <iostream>
#include <string>
using namespace std;

struct StreetAddress
{
   int house_number;
   string street_name;
};

void print_address(StreetAddress address, bool number_first);

int main()
{
    StreetAddress white_house;
    white_house.house_number = 1600;
    white_house.street_name = "Pennsylvania Avenue";
    print_address(white_house, true);
    cout << endl << "Expected: 1600 Pennsylvania Avenue" << endl;
    StreetAddress train_station;
    train_station.house_number = 1;
    train_station.street_name = "Bahnhofstraße";
    print_address(train_station, false);
    cout << endl << "Expected: Bahnhofstraße 1" << endl;
    return 0;
}

void print_address(StreetAddress address, bool number_first)
{
   //code here
}

Currently in the code here section, I have this:

void print_address(StreetAddress address, bool number_first)
{
   StreetAddress s;
   if(number_first == true)
      cout << s.house_number << " " << s.street_name;
   else if (number_first == false)
      cout << s.street_name << " " << s.house_number;
}

I'm getting numbers instead of what I want. What's the problem here? I'm failing to see the issue.

Small sidenote: if(number_first == true) can be simplified to if(numer_first) and you can simplify the else if to an else without any conditions. — Lukas-T
– Lukas-T, Commented Sep 2, 2021 at 5:51

Jeremy Friesner · Accepted Answer · 2021-09-02 05:15:14Z

3

Your print_address function is declaring a local variable StreetAddress s and leaving it uninitialized, and then trying to print out the uninitialized "data" it contains.

I think what you intended was to print out the fields in the address argument, instead.

answered Sep 2, 2021 at 5:15

Jeremy Friesner

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3 Comments

Jeremy Friesner Over a year ago

reference address.house_number and address.street_name in your cout lines, rather than s.house_number and s.street_name. (In fact, get rid of the StreetAddress s; line entirely, as you don't need it and its presence is what is allowing your program to compile and do the wrong thing, rather than giving you a helpful compile-time error)

ASM student Over a year ago

Ah, I had thought that I would have to somehow initialize the structure in the function itself. Is using the address reference due to the structure being initialized in the parameters?

Jeremy Friesner Over a year ago

Yes; you could alternatively do StreetAddress s = address; then you would have two identical StreetAddress objects (address and s) and you could print data from either of them. There’s no benefit in this case to making a second copy, though.

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