Hi,all
my guile1.9.14 output like this:
when I studied the format procedure following the mannual:
====== mannual start=====
~f 

If overflowchar and width are both given and if the output would exceed width, then that many overflowchars are printed instead of the value.

               (format #t "~5,,,'xf" 12345) -| 12345
               (format #t "~4,,,'xf" 12345) -| xxxx           <- bug
====== mannual end=====
but i got like this:
====== repl start=====
scheme@(guile-user)> (format #f "~5,,,'xf" 12345)
"xxxxx"
scheme@(guile-user)> (format #f "~6,,,'xf" 12345)
"12345."
====== repl end=====