The procedure ExpandTabs replaces tab characters in a string with spaces according to a given tab stop specification.

The tab stop specification must be either a positive integer, or a strictly increasing list of positive integers. If the tab stop is a positive integer $n$, then tabs are set every $n$ columns. If the tab stop specification is a list $\[\mathrm{n1},\mathrm{n2},...,\mathrm{nk}\]$, then tabs are set at columns $\mathrm{n1}$, $\mathrm{n2}$, ..., and $\mathrm{nk}$. The default value for the optional second argument is the positive integer $8$.

A string is returned in which tabs in the original input string s have been replaced by spaces to the indicated tab stops; the input string is not modified.

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.

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

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\right)$

$''a\; b\; c\; d\; e''$

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\,8\right)$

$''a\; b\; c\; d\; e''$

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\,4\right)$

$''a\; b\; c\; d\; e''$

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\,\left[2\,4\,8\,16\,32\,64\right]\right)$

$''a\; b\; c\; d\; e''$

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\,\left[2\,4\,8\right]\right)$

$''a\; b\; c\; d\; e''$

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash nd\backslash te''\,\left[2\,4\,8\,16\,32\,64\right]\right)$

$''a\; b\; c\; d\; e''$

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\,\left[2\,8\,4\right]\right)$

Error, (in StringTools:-ExpandTabs) tab stops must be strictly increasing

$\mathrm{ExpandTabs}\left(''a\backslash tb\backslash tc\backslash td\backslash te''\,\left[2\,8\,8\right]\right)$

Error, (in StringTools:-ExpandTabs) tab stops must be strictly increasing