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I want to convert:

  1. A simple unsigned char [] to string

  2. Then again to unsigned char

This is my code:

// This is the original char unsigned char data[14] = { 0x68,0x65,0x6c,0x6c,0x6f,0x20,0x63,0x6f,0x6d,0x70,0x75,0x74,0x65,0x72, }; // This convert to string string str(data, data + sizeof data / sizeof data[0]); // And this convert to unsigned char again unsigned char* val = new unsigned char[str.length() + 1]; strcpy_s(reinterpret_cast<char *>(val), str.length()+1 , str.c_str());

The problem is with the 2nd part, It wont convert the string to unsigned char like it was before. I think this img from locals in debug helps

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    It works. What's the problem, exactly? Commented Apr 9, 2018 at 11:52
  • val does contain a copy of data. Visual Studio's debug window is just not showing it as an array. If you add val,14 to your watch list, it will be shown as an array. Commented Apr 9, 2018 at 11:54
  • @KompjoeFriek Thank you i saw it now, I want to use val somewhere and it must be exactly like data Commented Apr 9, 2018 at 12:11

1 Answer 1

Reset to default
1

One way:

#include <string> #include <utility> #include <cstring> #include <memory> #include <cassert> int main() { // This is the original char unsigned char data[14] = { 0x68,0x65,0x6c,0x6c,0x6f,0x20,0x63,0x6f,0x6d,0x70,0x75,0x74,0x65,0x72, }; // This convert to string std::string str(std::begin(data), std::end(data)); // And this convert to unsigned char again auto size = std::size_t(str.length()); auto new_data = std::make_unique<unsigned char[]>(size); std::memcpy(new_data.get(), str.data(), size); // check for (auto f1 = data, f2 = new_data.get(), e1 = f1 + size ; f1 != e1 ; ++f1, ++f2) { assert(*f1 == *f2); } }
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7 Comments

Can you please copy data to a new unsigned char in the last part ?
It gave me hello computerýýýý· in result ! weird
@AidenStewart remember that new_data will not be null terminated.
Since C++11 "The returned array is null-terminated, that is, data() and c_str() perform the same function." (from en.cppreference.com/w/cpp/string/basic_string/data ), so you could copy size + 1 elements to null-terminate new_data.
@Bob__ right. But look how many characters I copied out of the string. The exact number that were copied in. You'd have to increase the value of size by 1 to accommodate and copy out the null terminator.
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