lib: implements `Float::to_precision` in a non native way

[nit.git] / lib / standard / string.nit

diff --git a/lib/standard/string.nit b/lib/standard/string.nit
index dc00916..0bc9e94 100644 (file)
--- a/lib/standard/string.nit
+++ b/lib/standard/string.nit
@@ -783,7 +783,7 @@ end
 redef class Float
        # Pretty print self, print needed decimals up to a max of 6.
        redef fun to_s do
-               var str = to_precision( 6 )
+               var str = to_precision( 3 )
                var len = str.length
                for i in [0..len-1] do
                        var j = len-1-i
@@ -800,7 +800,30 @@ redef class Float
        end
 
        # `self' representation with `nb' digits after the '.'.
-       fun to_precision(nb: Int): String import String::from_cstring `{
+       fun to_precision(nb: Int): String
+       do
+               if nb == 0 then return self.to_i.to_s
+               var f = self
+               for i in [0..nb[ do f = f * 10.0
+               if self > 0.0 then
+                       f = f + 0.5
+               else
+                       f = f - 0.5
+               end
+               var i = f.to_i
+               if i == 0 then return "0.0"
+               var s = i.to_s
+               var sl = s.length
+               if sl > nb then
+                       var p1 = s.substring(0, s.length-nb)
+                       var p2 = s.substring(s.length-nb, nb)
+                       return p1 + "." + p2
+               else
+                       return "0." + ("0"*(nb-sl)) + s
+               end
+       end
+
+       fun to_precision_native(nb: Int): String import String::from_cstring `{
                int size;
                char *str;