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  1. #include <iostream>
  2. #include <algorithm>
  3. #include <cstring>
  4.  
  5. struct A {
  6.     std::string data;   
  7.     A(std::string v) :data(std::move(v)) {}
  8.     void foo() {std::cout << data;}
  9. };
  10.  
  11. template<class T>
  12. struct reloc_ptr {
  13.     template<class U>
  14.     reloc_ptr(char*& base, int offset, U&& v) :base(&base), offset(offset) {new(get())T(std::forward<U>(v));}
  15.     T* get() const {return (T*)(*base+offset);}
  16.     T* operator->() const {return get();}
  17.     void destroy() {get()->~T();}
  18. private:
  19.     char** base;
  20.     int offset;
  21. };
  22.  
  23. int main() {
  24.     char* base = new char[1000];
  25.     //construct
  26.     reloc_ptr<A> clsA(base,4, "HI");
  27.     //test
  28.     clsA->foo();
  29.     //move base
  30.     char* other = new char[1000];
  31.     memcpy(other, base, 1000);
  32.     std::swap(base, other);
  33.     delete[] other;
  34.     //test
  35.     clsA->foo();
  36.     //cleanup
  37.     clsA.destroy();
  38.     delete[] base;
  39. }
  40.  
Success #stdin #stdout 0s 3028KB
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stdin
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Standard input is empty
stdout
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HIHI
https://ideone.com/4DNUGQ
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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