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  1. #include <iostream>
  2. #include <memory>
  3. #include <string>
  4.  
  5. using namespace std;
  6.  
  7. void string_example() {
  8.  
  9.     auto a = string("original value");
  10.  
  11.     auto b = a; // true copy by copying the value
  12.  
  13.     a = string("new value");
  14.  
  15.     cout << "a = " << a << endl;
  16.     cout << "b = " << b << endl;
  17.     cout << boolalpha << "&a == &b ? " << (&a==&b) << endl;
  18. }
  19.  
  20. void shared_ptr_example() {
  21.  
  22.     auto a = make_shared<string>("original value");
  23.  
  24.     auto b = a; // not a copy, just and alias
  25.  
  26.     *a = string("new value"); // and this gonna hurt b
  27.  
  28.     cout << "a = " << *a << endl;
  29.     cout << "b = " << *b << endl;
  30.     cout << boolalpha << "&a == &b ? " << (&a==&b) << endl;
  31. }
  32.  
  33. void shared_ptr_to_const_example() {
  34.  
  35.     auto a = make_shared<const string>("original value");
  36.  
  37.     auto b = a;
  38.  
  39.     //*a = string("new value"); // <-- now won't compile
  40.     a = make_shared<const string>("new value");
  41.  
  42.     cout << "a = " << *a << endl;
  43.     cout << "b = " << *b << endl;
  44.     cout << boolalpha << "&a == &b ? " << (&a==&b) << endl;
  45. }
  46.  
  47. int main() {
  48.  
  49.     cout << "--------------" << endl;
  50.     cout << "string example" << endl;
  51.     string_example();
  52.  
  53.     cout << "------------------" << endl;
  54.     cout << "shared_ptr example" << endl;
  55.     shared_ptr_example();
  56.  
  57.     cout << "---------------------------" << endl;
  58.     cout << "shared_ptr to const example" << endl;
  59.     shared_ptr_to_const_example();
  60. }
  61.  
Success #stdin #stdout 0s 3436KB
comments (?)
stdin 
Standard input is empty
stdout 
--------------
string example
a = new value
b = original value
&a == &b ? false
------------------
shared_ptr example
a = new value
b = new value
&a == &b ? false
---------------------------
shared_ptr to const example
a = new value
b = original value
&a == &b ? false
https://ideone.com/BtkbfR
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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