Answer:
backup() {
 read dirname;
 if [[ whereis . /`$dirname` 2>  sterr.exe]] Â
  then
    mkdir  $dirname
 for f in . / *.cpp
 do
  cp f "path_to_dirname"
  echo "file backup complete"
}
backup( )
Explanation:
The bash script above is used to backup C++ source files in a directory to a backup directory which is created if it does not exist, and copy's each .cpp file to backup, then sends a message to declare its completion.