The CountLines(file) command counts the number of lines from the current position in file to the end of file.

A line is defined to be zero or more characters delimited by the current file position, a new line character, and the end of file.  There is one exception to this definition: if the last character in the file is a newline, then the null string (zero characters) between this newline and the end of file is not considered a line. This definition is consistent with the behavior of ReadLine and readline.

An error is raised if file is not a valid descriptor or if it is the name of a file that does not exist.

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{WriteString}\right]\left(''foo''\,''1\backslash n2\backslash n3\backslash n4\backslash n5''\right)$

$9$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{Close}\right]\left(''foo''\right)\:$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{CountLines}\right]\left(''foo''\right)$

$5$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{ReadLine}\right]\left(''foo''\right)$

$''1''$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{CountLines}\right]\left(''foo''\right)$

$4$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{ReadLine}\right]\left(''foo''\right)$

$''2''$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{CountLines}\right]\left(''foo''\right)$

$3$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{ReadLine}\right]\left(''foo''\right)$

$''3''$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{CountLines}\right]\left(''foo''\right)$

$2$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{ReadLine}\right]\left(''foo''\right)$

$''4''$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{CountLines}\right]\left(''foo''\right)$

$1$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{ReadLine}\right]\left(''foo''\right)$

$''5''$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{CountLines}\right]\left(''foo''\right)$

$0$

$\mathrm{FileTools}\left[\mathrm{Text}\right]\left[\mathrm{Close}\right]\left(''foo''\right)\:$

$\mathrm{FileTools}\left[\mathrm{Remove}\right]\left(''foo''\right)\:$