This question is a follow up to C++ - Convert array of floats to std::string.
How to convert a std::string back to float array that was converted to string using reinterpret_cast.
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1 Answer
Get the string's backing data pointer from the c_str() method. Then reinterpret_cast it back to the float pointer.
const float* array_of_floats = reinterpret_cast<const float*>(str.c_str());
int len = str.size() / sizeof(float);
In general, serializing binary data (such as array of floats) into string can work, but is at best weird and more likely ill-advised. You are better off using std::vector<uint8_t> as an array of bytes to hold your floating pointer data instead of an instance of a string.
4 Comments
Saurabh Saxena
Getting following error main.cpp:20:16: error: reinterpret_cast from 'const std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::value_type *' (aka 'const char *') to 'float *' casts away qualifiers float *d = reinterpret_cast<float*>(s.c_str()); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
selbie
ahhh… I forgot.
c_str() returns a const char*. Therefore, you need to cast to a const float*. Answer updated.
john
@SaurabhSaxena be advised that the
array_of_floats pointer is only valid as long as the underlying string exists and is unchanged. It might be better to copy the floats into a separate array instead of relying on a pointer to the string data.Saurabh Saxena
@john I am planning to store string in db.