How to copy text file in C or C++?

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.

Answer 2

Just "buffer by buffer", copy files in binary mode and read/write X bytes long parts. I think that fastest solution is to just use copy function of C language itself or system call.

Largest buffer will provide you less HDD find for data operations (faster copying) but more RAM usage.