Question

I want to search for string that occurs between a certain string. For example,

\start

\problem{number}
\subproblem{number}

/* strings that I want to get */

\subproblem{number}

/* strings that I want to get */

\problem{number}
\subproblem{number}
       ...
       ...
\end

More specifically, I want to get problem number and subproblem number and strings between which is answer.

I somewhat came up with expression like

'(\\problem{(.*?)}\n)? \\subproblem{(.*?)} (.*?) (\\problem|\\subproblem|\\end)'

but it seems like it doesn’t work as I expect. What is wrong with this expression?

Answer 1

This one:

(?:\\problem\{(.*?)\}\n)?\\subproblem\{(.*?)\}\n+(.*?)\n+(?=\\problem|\\subproblem|\\end)

returns three matches for me:

Match 1:

group 1: "number"
group 2: "number"
group 3: "/* strings that I want to get */"

Match 2:

group 1: null
group 2: "number"
group 3: "/* strings that I want to get */"

Match 3:

group 1: "number"
group 2: "number"
group 3: "       ...\n       ..."

---

However I’d rather parse it in two steps.

First find the problem’s number (group 1) and content (group 2) using:

\\problem\{(.*?)\}\n(.+?)\\end

Then find the subproblem’s numbers (group 1) and contents (group 2) inside that content using:

\\subproblem\{(.*?)\}\n+(.*?)\n+(?=\\problem|\\subproblem|\\end)