string - subseq (LISP) 的简单问题

Question

我刚开始使用 LISP，具有 C 语言背景。到目前为止它很有趣，尽管学习曲线令人难以置信(我也是 emacs 新手)。

无论如何，我在解析来自 c 源代码的 include 语句时遇到了一个愚蠢的问题——如果有人可以对此发表评论并提出解决方案，那将大有帮助。

(defun include-start ( line )
    (search "#include " line))

(defun get-include( line )
  (let ((s (include-start line)))
    (if (not (eq NIL s))
      (subseq line s (length line)))))

(get-include "#include <stdio.h>")

我希望最后一行返回

"<stdio.h>"

然而实际结果却是

"#include <stdio.h>"

有什么想法吗？

Answer 1

(defun include-start (line)
  "returns the string position after the '#include ' directive or nil if none"
  (let ((search-string "#include "))
    (when (search search-string line)
      (length search-string))))

(defun get-include (line)
  (let ((s (include-start line)))
    (when s
      (subseq line s))))