Returns the substring of s that starts at i and continues until j; i and j
can be negative. If j is absent, then it is assumed to be equal to -1
(which is the same as the string length). In particular, the call
string.sub(s,1,j) returns a prefix of s with length j, and string.sub(s,
-i) (for a positive i) returns a suffix of s with length i.
If, after the translation of negative indices, i is less than 1, it is
corrected to 1. If j is greater than the string length, it is corrected to
that length. If, after these corrections, i is greater than j, the function
returns the empty string.
Returns the substring of s that starts at i and continues until j; i and j can be negative. If j is absent, then it is assumed to be equal to -1 (which is the same as the string length). In particular, the call string.sub(s,1,j) returns a prefix of s with length j, and string.sub(s, -i) (for a positive i) returns a suffix of s with length i.
If, after the translation of negative indices, i is less than 1, it is corrected to 1. If j is greater than the string length, it is corrected to that length. If, after these corrections, i is greater than j, the function returns the empty string.