Question

I have fixed length char array used to store my decoded data. Once finish decoding, I want to copy content of the char array to a char vector for later use. When debugging to the line of “std:copy(…)” an error occurred. What’s wrong with my std::copy usage?

Thank you!

std::vector<char> m_cCalibrationID;
char cCalibrationID[5];
memcpy(cCalibrationID, pszData, 4);
cCalibrationID[4] = 0;

// Copy to vector
std::copy ( cCalibrationID, cCalibrationID + 4, m_cCalibrationID.begin() );

Answer 1

Ignoring that you named them the same thing and pretending you didn’t, you need to allocate space for your vector first:

char arr[5];
memcpy(arr, pszData, 4);
arr[4] = 0;

std::vector<char> vec(5); // contains five usable elements
std::copy(arr, arr + 5, vec.begin());
//                 ^^^  should be + 5, not + 4, to get null terminator

Or you can use std::back_inserter:

char arr[5];
memcpy(arr, pszData, 4);
arr[4] = 0;

std::vector<char> vec; // contains zero usable elements
vec.reserve(5); // reserve space ahead of time
std::copy(arr, arr + 5, std::back_inserter(vec));

That will push_back each copied element. That said, why not skip the middleman?

std::vector<char> vec(5);
std::copy(pszData, pszData + 4, vec.begin());
// vec[4] already initialized to zero