About references in C++.

[Sebouh]

Hi all. I'm currently learning C++ from a tutorial C to C++. I have a question on references. More precisely, i'm confused why this code gives the following result.

#include <iostream>
#include <cstring>
using namespace std;
 
class person
{
public:
 
   char *name;
   int age;
 
   person (char *n = "no name", int a = 0)
   {
      name = new char[100];
      strcpy (name, n);
      age = a;
   }
 
   person (person &s)               // The COPY CONSTRUCTOR
   {
      name = new char[100];
      strcpy (name, s.name);
      age = s.age;
   }
 
   ~person ()
   {
      delete [] name;
   }
};
 
void foo(person p)
{
   cout << p.name << ", age " << p.age << endl << endl;
}
 
person &bar()
{
    return person("Todd", 15);
}
 
int main ()
{
   person k ("John", 56);
   cout << k.name << ", age " << k.age << endl << endl;
 
   foo(k); 
 
   person m(k);
 
   person n = bar();
    foo (n);
 
   return 0;
}
 

result:
------------------------------------------------------
C:\Documents and Settings\Sebouh>C:\my_cpp_tests\cpp_test\debug\cpp _test.exe
John, age 56

John, age 56

John, age 4212483 <----------------- WHY??
-----------------------------------------------------

why not Todd?


Thanks

[JosAH]

Your function bar attempts to return a reference to a local variable of type person.
After functions have returned all local variables have gone and destructed so your
reference refers to garbage.

kind regards,

Jos

[Sebouh]

So is it "by chance" that i get John?

[JosAH]

So is it "by chance" that i get John?

Yep, the memory where that object resided on the stack is gone, it's no more,
it's pushing up the daisies, it shuffled off its mortal coil, it's gone to meet its
maker ;-) The content of that memory could be anything.

kind regards,

Jos

[Sebouh]

Yep, the memory where that object resided on the stack is gone, it's no more,
it's pushing up the daisies, it shuffled off its mortal coil, it's gone to meet its
maker ;-) The content of that memory could be anything.

kind regards,

Jos

Heh, alright then.
Thanks.