The SubString(s, r) command returns a substring of string s specified by range r. A substring is a sequence of characters that occurs contiguously in the original string from which it is selected.

The range r must have integer endpoints. Range indexing for this function is similar to substring selection via the $s_{a..b}$ notation. For more information about range indexing, see selection.

The main difference between Substring and the Maple built-in substring procedure is that, when passed a symbol as the first argument, substring returns a symbol by default, whereas SubString always returns a string.

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.

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

$\mathrm{SubString}\left(''abcdef''\,2..2\right)$

$''b''$

$\mathrm{SubString}\left(''abcdef''\,3..5\right)$

$''cde''$

$\mathrm{SubString}\left(\mathrm{abcdef}\,3..5\right)$

$''cde''$

$\mathrm{SubString}\left(''abcdef''\,-5..-3\right)$

$''bcd''$