floatstring.scm

#|
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|#
;; formatting of floating numbers

(define (float->string x p)
  (let* ((pe (macro-flo (expt 10 (min 10 p))))
         (s (number->string (fl/ (flfloor (fl+ (fl* (macro-flo x) pe) 0.5)) pe)))
         (sl (string-length s))
         (b (substring s 0 1))
         (e (substring s (- sl 1) sl)))
    (string-append (if (string=? b ".") "0" "")
       (if (string=? e ".") (substring s 0 (- sl 1)) s))))

;; padstring 100 2 >  100.00

(define (float->zeropaddedstring x p) 
  (let* ((s (float->string x p))
         (tmp (string-split s #\.))
         (decimal? (= (length tmp) 2))
         (decimals (if decimal? (cadr tmp) ""))
         (missing  (- p (string-length decimals)))
         (padding  (if (> missing 0) (make-string missing #\0) "")))
    (string-append s (if (not decimal?) "." "") padding)))


(c-declare  #<<end-of-c-declare

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static char valstr[16];

static char *double_to_choppedstring(double val, int precision)
{
  memset(valstr,0,16);
  // NOTE: snprintf in some versions of mingw is broken! fall back on _snprintf (the MS version)
#ifdef WIN32
  _snprintf(valstr,16,"%f",val);
#else
  snprintf(valstr,16,"%f",val);
#endif
  int p=precision;
  if (val<0) p++;
  valstr[p]=0;
  if (valstr[p-1]=='.') valstr[p-1]=0;
  return valstr;
}

end-of-c-declare
)

(define (float->choppedstring v p) ((c-lambda (double int) char-string "double_to_choppedstring") (macro-flo v) p))

;; eof