Elisp: skip-chars-forward vs re-search-forward

skip-chars-forward vs re-search-forward

• Suppose you have a URL. Cursor is somewhere on the URL, or at the beginning of the URL or at the end of the URL.
• You want to find the beginning position of the URL.

• If you use re-search-backward for whitespace, you have to move the cursor forward to the end of whitespace. And you have to consider if the URL is at the beginning of file with no character before it.
• With skip-chars-backward, you don't have to do this extra check.

;; compare skip-chars-forward vs re-search-forward

(save-excursion
  (skip-chars-backward "^[:space:]")
  (setq xbegin (point))
  (skip-chars-forward "^[:space:]")
  (setq xend (point)))

(save-excursion
  (re-search-backward "[[:space:]]" nil 1)
  (setq xbegin (1- (point)))
  (re-search-forward "[[:space:]]" nil 1)
  (setq xend (1- (point))))