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  1. #include <algorithm>
  2. #include <chrono>
  3. #include <iostream>
  4. #include <fstream>
  5. #include <vector>
  6. #include <cmath>
  7. #include <cstring>
  8. #include <numeric>
  9.  
  10.  
  11. struct my_data {
  12. 	uint32_t some_value;
  13. 	std::vector<uint32_t> some_vector;
  14.  
  15. 	my_data (uint32_t v, std::vector<uint32_t> vec) : 
  16. 			some_value(v), some_vector(std::move(vec)) {};
  17. };
  18.  
  19.  
  20.  
  21. int main() {
  22.  
  23. 	std::vector<my_data> all_data;
  24. 	for (size_t i = 0; i < 10; ++i) {
  25. 		std::vector<uint32_t> temp = {1, 2, 3, 4, 5};
  26. 		uint32_t x = 3;
  27. 		all_data.emplace_back(x, temp);
  28. 	}
  29.  
  30. 	// Now write it to file, two ways...
  31. 	std::ofstream out("tmp", std::ofstream::binary);
  32. 	for (size_t i = 0; i < 10; ++i) {
  33. 		// Works OK
  34. 		out.write((char *)all_data[i].some_vector.data(), all_data[i].some_vector.size() * sizeof(uint32_t));
  35.  
  36. 		// Does not work, gives garbage values
  37. 		out.write((char *)&all_data[i].some_vector[0], all_data[i].some_vector.size() * sizeof(uint32_t));
  38.  
  39. 	}
  40.  
  41. }
Success #stdin #stdout 0s 15240KB
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https://ideone.com/8jC1Dl
language:
C++14 (clang 8.0)
created:
5 years ago
visibility:
public

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