Merge pull request #113 from lpbak/issue_107

Closes #107

Author: maciejhirsz

src/util/print_dec.rs

@@ -74,7 +74,7 @@ pub unsafe fn write<W: io::Write>(wr: &mut W, positive: bool, mut n: u64, expone
             )
         );
     } else if exponent < 0 {
-        let mut e = -exponent as u16;
+        let mut e = safe_abs(exponent);
 
         // Decimal number with a fraction that's fully printable
         if e < 18 {
@@ -215,3 +215,11 @@ pub unsafe fn write<W: io::Write>(wr: &mut W, positive: bool, mut n: u64, expone
     try!(wr.write_all(b"e"));
     write(wr, true, e, 0)
 }
+
+fn safe_abs(x : i16) -> u16 {
+    if let Some(y) = x.checked_abs() {
+        y as u16
+    } else {
+        i16::max_value() as u16 + 1u16
+    }
+}

tests/number.rs

@@ -126,3 +126,9 @@ fn as_fixed_point_i64() {
 fn convert_f64_precision() {
     assert_eq!(Number::from_parts(true, 4750000000000001, -18), 0.004750000000000001);
 }
+
+#[test]
+fn issue_107() {
+    let n = Number::from_parts(true, 1, -32768);
+    assert_eq!(format!("{}", n), "1e-32768");
+}