Question

When trying to copy a text file A to another file B, there may have several methods:
1) byte by byte
2) word by word
3) line by line

which one is more efficient?

Answer 1

Using buffers:

#include <fstream>

int main()
{
    std::ifstream    inFile("In.txt");
    std::ofstream    outFile("Out.txt");

    outFile << inFile.rdbuf();
} 

The C++ fstreams are buffered internally. They use an efficient buffer size (despite what people say about the efficiency of stream :-). So just copy one stream buffer to a stream and hey presto the internal magic will do an efficient copy of one stream to the other.

But learning to do it char by char using std::copy() is so much more fun.