How to delete a pointer after returning its value inside a function

Dynamic arrays are freed using delete[]:

char* block = ReadBlock(...);
// ... do stuff
delete[] block;

Ideally however you don’t use manual memory management here:

std::vector<char> ReadBlock(std::fstream& stream, int size) {
    std::vector<char> memblock(size);
    stream.read(&memblock[0], size);
    return memblock;
}