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

If you do word-by-word or line-by line you can hardly reconstruct the original file since the are many forms of line breaks (\r, \n, \r\n) and spaces (\p, \f, 0x32) embedded in text files which you are risking to loose this way.

The most efficient way to copy files is to use byte-buffers. The larger the buffer, the more efficient the copying will be, as long as your buffer size isn't bigger than hard disk internal buffer size (today mostly ~8mb).