Replace a match only till some other match is found

Question

Aiming to convert first row of a html table from to tags.

So, I wrote the following code.

(defun tdtoth ()
  (if (search-forward "</tr>" nil t)
      (while (search-forward "td" nil t)
        (replace-match "th" 1))))

And executed it while I was on in the following text:

<tr>
  <td> Some text </td>
  <td> Another thing </td>
</tr>

The idea being search for </tr> only once and while that is not happening, replace every td with th

But that code does not work. What is wrong and how do I set it right?

Answer 1

After my comment about not needing the function in most cases I also want to give an answer to your actual question.

One of the many ways to replace all occurences of td-tags with th-tags starting at point and stopping at a closing tr-tag is shown below. The most important differences to your solution are:

• You need to keep point's position when you search for the end tag </tr> (e.g., with save-excursion).
• You need to restrict your search for <td> to the region between point and the found end position, e.g., with the BOUND-argument of search-forward.

(defun dttoth ()
  "Replace dt by th starting at point and stopping at </tr>."
  (interactive)
  (let ((bound (save-excursion (search-forward "</tr>" nil t))))
    (when bound
      (while (re-search-forward "<[/]?\\(td\\)>" bound t)
        (replace-match "th" t nil nil 1)))))