Assume that the input source is a text file consisting of a sequence of newline character-terminated lines. the function copies, line by line, the entire content of the data source associated with the first argument to the data target associated with the second argument. it returns the number of lines read in. if it the third parameter, the bool is true, every line that is output is preceded by a 6-position field holding the line number (an integer) followed by a space and then the actual line. if the last argument, the int is 2 or more, it specifies the line spacing: for example, it is 3, there are two blank lines output after each line printed. these blank lines are not numbered.