返回的地址始终为 0 而不是实际值

Question

Here is the simple code:

int *ad_return()
{
    int a=600;
    cout << &a << endl;
    return &a;
}

int main()
{
    cout << ad_return();
    return 0;
}

The output is unexpected. The first cout prints an address that looks like a address but the cout that is in the main prints a legit 0. I couldn't find an explanation anywhere.

Answer 1

Based on what I have experimented, I have concluded the following:

Since the address of a local variable that has already went out of scope is undefined, it seems that gcc and g++ decided to implement a feature that sets this to zero (probably to make sure that the code segfaults instead of generating thoroughly bizarre behaviour). It does not do this in clang, but the value is undefined so both of these compilers are operating in accordance with the standard.

Answer 2

Try This Code.
There was problem you were trying to access address of a local variable a it is not accessible out side of the function as_return(). So declare it in global so that it is accessible to everyone.

   #include<iostream>
  using namespace std;
  int a;
  int *ad_return()
  {
   a=600;
   cout << &a << endl;
   return &a;
  }

  int main()
  {
   cout << ad_return();
   return 0;
   }

.

I hope you got answer