C++ String to byteArray Convertion and Addition - c++

Question

I have a string which I want to convert to a byteArray, and then I want this byteArray to be added to another byteArray, but at the beginning of that byteArray.
Let us say this is the string I have
string suffix = "$PMARVD";
And this is the existing byteArray that I have (ignore the object there, it is a .proto object which is irrelevant now):
int size = visionDataMsg.ByteSize(); // see how big is it
char* byteArray = new char[size]; //create a bytearray of that size
visionDataMsg.SerializeToArray(byteArray, size); // serialize it
So what I want to do is something like this:
char* byteArrayforSuffix = suffix.convertToByteArray();
char* byteArrayforBoth = byteArrayforSuffix + byteArray;
Anyway of doing this in C++?
Edit: I should add that after the concatenation operation, the complete byteArrayforBoth is to be processed in:
// convert bytearray to vector
vector<unsigned char> byteVector(byteArrayforBoth, byteArrayforBoth + size);

Answer 1

the whole idea behind std::string is to wrap the C style strings (null terminated charcaters/bytes array) with a class that manages everything.
you can excess the inner characters array with std::string::data method. example :
std::string hello ("hello") , world(" world");
auto helloWorld = hello + world;
const char* byteArray = helloWorld.data();
EDIT:
ByteArray is a built-in type of char[] or unsigned char[], unlike Java or C#, you can't just "append" built-in byte array to another. as you suggested, you simply want a vector of unsigned characters. in this situation I would simply create a utility-function that utilizes push_back:
void appendBytes(vector<unsigend char>& dest,const char* characterArray,size_t size){
dest.reserve(dest.size() + size);
for (size_t i=0;i<size;i++){
dest.push_back(characterArray[i]);
}
}
now , with the objects you provided:
std::vector<unsigned char> dest;
appendBytes(dest, suffix.data(),suffix.size());
auto another = visionDataMsg.SerializeToArray(byteArray, size);
appendBytes(dest,another,size);

Answer 2

Scrap built-in arrays. You have vectors. Here is the fully working, type-safe solution which took me 3 minutes to type:
int size = visionDataMsg.ByteSize(); // see how big is it
std::vector<char> byteArray(size);
visionDataMsg.SerializeToArray(&byteArray[0], size); // serialize it
std::string str("My String");
byteArray.reserve(byteArray.size() + str.size());
std::copy(str.begin(), str.end(), std::back_inserter(byteArray));