The Length command computes the length of the string s. This is the same value as is returned by the global length command, but it accepts only strings.

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$\mathrm{Length}\left(''''\right)$

$0$

$\mathrm{Length}\left(''abcde''\right)$

$5$

$\mathrm{length}\left(''abcde''\right)$

$5$

$\mathrm{Length}\left(''aqueosalinocalcalinoetaceoaluminiumosecupreovitriolic''\right)$

$53$

$\mathrm{Length}\left(x^2\right)$

Error, invalid input: StringTools:-Length expects its 1st argument, s, to be of type string, but received x^2

$\mathrm{length}\left(x^2\right)$

$5$

$\mathrm{Length}\left(''d303251cembre''\right)$

$9$