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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <cstdlib>
  4. #include <cstring>
  5.  
  6. void dump(void *s, size_t size) {
  7.     unsigned char *buf = (unsigned char*)s;
  8.     for (size_t i=0; i<size; ++i) {
  9.         std::cout << std::hex << std::setw(2) << std::setfill('0') << (int)buf[i] << " ";
  10.     }
  11.     std::cout << std::endl;
  12. }
  13.  
  14. struct Test {
  15.     Test() : x(5) {
  16.         std::cout << "In c'tor:            ";
  17.         dump(this, sizeof(*this));
  18.         memset(this, 0, sizeof(*this));
  19.     }
  20.     virtual ~Test() {
  21.     }
  22.     int x;
  23. };
  24.  
  25.  
  26. int main() {
  27.     Test *t = (Test*)calloc(1, sizeof(Test));
  28.     std::cout << "Before construction: ";
  29.     dump(t, sizeof(Test));
  30.     new(t) Test;
  31.     std::cout << "After construction:  ";
  32.     dump(t, sizeof(Test));
  33.     return 0;
  34. }
Success #stdin #stdout 0.02s 2812KB
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stdin
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Standard input is empty
stdout
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Before construction: 00 00 00 00 00 00 00 00 
In c'tor:            00 8d 04 08 05 00 00 00 
After construction:  00 00 00 00 00 00 00 00
https://ideone.com/Zi6Osl
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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