seek

seek(handle, offset, [mode])

handle must be a file handle.

offset is an integer.

mode (optional) must be one of the 3 positions: HEAD, CURRENT, TAIL. Default mode is CURRENT.

Return the final position of the internal cursor if no exception is raised.

When the system reads data from a file or writes data to a file, the internal cursor moves forward. Users can manipulate the cursor manually with the seek function.

//  write a function to show the length of a file
def fileLength(f): file(f).seek(0, TAIL)
fileLength("test.txt");
// output
14

// move the internal cursor to the beginning of the file
fin=file("test.txt")
fin.readLine();
// output
Hello World!

fin.seek(0, HEAD);
// output
0

fin.readLine();
// output
Hello World!