LengthString( string )
LengthString returns the length of the string string. The length of
a string is the number of characters in the string. Escape sequences
(see Strings and Characters) are just a two character representation
for a single character, and are thus counted as single character by
LengthString.
gap> LengthString( "" );
0
gap> LengthString( "Hello" );
5
gap> LengthString( "Hello world.\n" );
13
Because strings are now lists, Length (see Length) does exactly the
right thing, and the function LengthString is obsolete.
GAP 3.4.4