# HG changeset patch
# User jbe
# Date 1452790893 -3600
# Node ID 387a303918a6b94ae880c87ce6f00038db289693
# Parent  52ebde158c92091b5d376fa50c7bfc957ff7a3cc
Handle special corner case for integral floats in json.export(...)

diff -r 52ebde158c92 -r 387a303918a6 libraries/json/json.c
--- a/libraries/json/json.c	Thu Jan 14 17:40:49 2016 +0100
+++ b/libraries/json/json.c	Thu Jan 14 18:01:33 2016 +0100
@@ -1119,10 +1119,16 @@
       if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
       // throw error if number is positive or negative infinity:
       if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
-      // determine necessary precision to represent double precision floating point number:
-      sprintf(numstr, "%.15g", num);  // NOTE: e.g. 0.009 should not be 0.008999999999999999
-      if (strtod(numstr, NULL) != num) sprintf(numstr, "%.16g", num);
-      if (strtod(numstr, NULL) != num) sprintf(numstr, "%.17g", num);
+      // check if float is integral:
+      if (trunc(num) == num) {
+        // if yes, use maximum precision:
+        sprintf(numstr, "%.17g", num);  // NOTE: e.g. 12345678901234560
+      } else {
+        // determine necessary precision to represent double precision floating point number:
+        sprintf(numstr, "%.15g", num);  // NOTE: e.g. 0.009 should not be 0.008999999999999999
+        if (strtod(numstr, NULL) != num) sprintf(numstr, "%.16g", num);
+        if (strtod(numstr, NULL) != num) sprintf(numstr, "%.17g", num);
+      }
       // add string encoding of the number to the output buffer:
       luaL_addstring(&buf, numstr);
 #if LUA_VERSION_NUM >= 503