formatting - 前面有符号的零填充小数的格式字符串？

Question

是否有格式字符串用于用前面的符号填充小数点？

(format nil ? 5) => "+0005"
(format nil ? -5) => "-0005"

我找到的最接近的是

(format nil "~4,'0@d" 5) => "00+5"
(format nil "~4,'0@d" -5) => "00-5"

Answer 1

这是自定义打印机功能的草稿:

(defun signed-padding (stream data colonp atsignp &optional (padding 0))
  (declare (ignore colonp atsignp))
  (format stream "~:[+~;-~]~v,'0d" (minusp data) padding (abs data)))

...还有一个例子:

(values
 (format nil "~v/signed-padding/" 20 330)
 (format nil "~5/signed-padding/" -4))

"+00000000000000000330"
"-00004"

您可能可以添加更多检查和选项。