I have an array of floats with a fixed length. Now I want to convert that array to a binary string.
I cannot use const char *
because my string will contain null-bytes. How would I use memcpy in that case? I have already tried a reinterpret_cast<string *>
, but that won't work because the string is also/only storing pointers to the begin and end of the data (correct me if I am wrong).
I'm already constructing an empty string:
string s;
s.resize(arr_size);
But how would I copy an array of floats to that string?
Basically, I want to dump the memory region of a fixed float array to a string.
Don't be to hard with me, I'm still learning c++
Like this:
#include <algorithm>
#include <string>
float data[10]; // populate
std::string s(sizeof data);
char const * p = reinterpret_cast<char const *>(data);
std::copy(p, p + sizeof data, &s[0]);
Note that sizeof data
is the same as 10 * sizeof(float)
, ie the number of bytes in the array.
Update: As suggested by James, you can do even better and write it all in one go:
char const * p = reinterpret_cast<char const *>(data);
std::string s(p, p + sizeof data); // beginning + length constructor
Or even:
#include <iterator>
std::string s(reinterpret_cast<char const *>(std::begin(data)), // begin + end
reinterpret_cast<char const *>(std::end(data))); // constructor
Getting all of the bytes of the array into a string is easy:
std::string
bitwiseDump( float const* begin, float const* end )
{
return std::string( reinterpret_cast<char const*>( begin ),
reinterpret_cast<char const*>( end ) );
}
But why? There's nothing you can do with the string except copy it back into an array of the same type. (And even for that use, std::vector<char>
or std::vector<unsigned char>
would be more natural. And less obfuscating.)
Take a look at this...
#include <iostream>
#include <array>
#include <string>
int main()
{
std::string floatString;
std::array<float, 5> data = {1.1f, 2.2f, 3.3f, 4.4f, 5.5f};
for (auto& element : data)
floatString.append(std::to_string(element));
std::cout << floatString;
std::cin.get();
}
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