Pad Between Strings

Function Syntax (LM:PadBetween <s1> <s2> <ch> <ln>)
Current Version 1.0
Arguments
Symbol Type Description
s1,s2 String Strings to be concatenated
ch String Character for padding
ln Integer Minimum length of returned string
Returns
Type Description
String Concatenation of strings s1,s2 padded in between to a minimum length

Program Description

This function returns a string of a minimum specified length which is the concatenation of two supplied strings, padded between using a supplied character.

This function may be used to generate a string of a known length consisting of two elements of unknown length - such behaviour is useful when printing reports or lists to the command-line. As an example, this function is extensively utilised in my Dynamic Block Counter program, to generate the report of the block quantities at the command-line.

As expected, the iterative version of the program is approximately 2.5 times faster than the recursive version, but I have included the recursive version to provide some variation on how the result can be achieved.

Recursive Version

Select all
;;---------------------=={ Pad Between }==--------------------;;
;;                                                            ;;
;;  Returns a string of a minimum specified length which is   ;;
;;  the concatenation of two supplied strings padded to a     ;;
;;  desired length using a supplied character.                ;;
;;------------------------------------------------------------;;
;;  Author: Lee Mac, Copyright  2011 - www.lee-mac.com       ;;
;;------------------------------------------------------------;;
;;  Arguments:                                                ;;
;;  s1,s2 - strings to be concatenated                        ;;
;;  ch    - character for padding                             ;;
;;  ln    - minimum length of returned string                 ;;
;;------------------------------------------------------------;;
;;  Returns:  Concatenation of s1,s2 padded to a min length   ;;
;;------------------------------------------------------------;;

(defun LM:PadBetween ( s1 s2 ch ln )
    (if (< (+ (strlen s1) (strlen s2)) ln)
        (LM:PadBetween (strcat s1 ch) s2 ch ln)
        (strcat s1 s2)
    )
)

Iterative Version

Select all
;;---------------------=={ Pad Between }==--------------------;;
;;                                                            ;;
;;  Returns a string of a minimum specified length which is   ;;
;;  the concatenation of two supplied strings padded to a     ;;
;;  desired length using a supplied character.                ;;
;;------------------------------------------------------------;;
;;  Author: Lee Mac, Copyright  2011 - www.lee-mac.com       ;;
;;------------------------------------------------------------;;
;;  Arguments:                                                ;;
;;  s1,s2 - strings to be concatenated                        ;;
;;  ch    - character for padding                             ;;
;;  ln    - minimum length of returned string                 ;;
;;------------------------------------------------------------;;
;;  Returns:  Concatenation of s1,s2 padded to a min length   ;;
;;------------------------------------------------------------;;

(defun LM:PadBetween ( s1 s2 ch ln )
    (
        (lambda ( a b c )
            (repeat (- ln (length b) (length c)) (setq c (cons a c)))
            (vl-list->string (append b c))
        )
        (ascii ch)
        (vl-string->list s1)
        (vl-string->list s2)
    )
)

Example Function Call

_$ (LM:PadBetween "String1" "String2" "." 30)
"String1................String2"

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Designed & Created by Lee Mac © 2010