I trying to get an input to format a certain way. For example input:
Before:
"12/4"
I need a space after each letter in the string.
After:
" 12 / 4 "
Another example:
Before
"-10/-4*5"
After
" -10 / -4 * 5 "
Before
6*-8/(-4+2)
After
6 * -8 / ( -4 + 2 )
I use the spacing to parse and split the input but if theirs not spacing then I can't split by space.
We can assume that + or - is not unary when there is digit or expression in parenthesis before it. Rest of operators, like * / ^ can't be unary so they always should be surrounded with spaces.
Using above assumptions you can create something like
String text = "-10/-4*+5+6+(1*2)-3^2";
String formatted = text.replaceAll("(?<=[\\d)])[-+]|[*/^]", " $0 ");
System.out.println(formatted);
Output:
-10 / -4 * +5 + 6 + (1 * 2) - 3 ^ 2
^^^ ^^ ^^ these are not changed
Explanation: we want to surround with spaces only non-unary operators so
(?<=[\\d)])[-+] - we are checking if before - or + there is any digit or ) using look-behind (?<=[\\d)])[*/^] we accept any of *, /, ^ as non-unary symbols which need to be surrounded by spaces - you can add here more symbols if you like for example ( ). " $0 " - here $0 represents match from group 0 (match from entire regex) so we are simply replacing operator found by regex with the same operator but surrounded with spaces.