c++ - Converting a string to uint8_t array in C++

Question

I want an std::string object (such as a name) to a uint8_t array in C++. The function reinterpret_cast<const uint8_t*> rejects my string. And since I'm coding using NS-3, some warnings are being interpreted as errors.

Answer 1

If you want a pointer to the string's data:

reinterpret_cast<const uint8_t*>(&myString[0])

If you want a copy of the string's data:

std::vector<uint8_t> myVector(myString.begin(), myString.end());
uint8_t *p = &myVector[0];

Answer 2

String objects have a .c_str() member function that returns a const char*. This pointer can be cast to a const uint8_t*:

std::string name("sth");

const uint8_t* p = reinterpret_cast<const uint8_t*>(name.c_str());

Note that this pointer will only be valid as long as the original string object isn't modified or destroyed.

Answer 3

If you need an actual array (not a pointer, as other answers have suggested; the difference is explained very nicely in this answer), you need to use std::copy from <algorithm>:

std::string str = "foo";
uint8_t arr[32];
std::copy(str.begin(), str.end(), std::begin(arr));