commit 788b25115715340613d1e7139837a51cd429c000
parent 318575627f5a38328e38acf23733c53abfe65be1
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 13 Jun 2013 16:32:27 -0300
'math.random' operates with integers when used for integer results
(1 or 2 parameters)
Diffstat:
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/lmathlib.c b/lmathlib.c
@@ -1,5 +1,5 @@
/*
-** $Id: lmathlib.c,v 1.85 2013/05/06 17:22:55 roberto Exp $
+** $Id: lmathlib.c,v 1.86 2013/05/26 13:45:24 roberto Exp roberto $
** Standard mathematical library
** See Copyright Notice in lua.h
*/
@@ -204,26 +204,28 @@ static int math_random (lua_State *L) {
/* the `%' avoids the (rare) case of r==1, and is needed also because on
some systems (SunOS!) `rand()' may return a value larger than RAND_MAX */
lua_Number r = (lua_Number)(rand()%RAND_MAX) / (lua_Number)RAND_MAX;
+ lua_Integer low, up;
switch (lua_gettop(L)) { /* check number of arguments */
case 0: { /* no arguments */
lua_pushnumber(L, r); /* Number between 0 and 1 */
- break;
+ return 1;
}
case 1: { /* only upper limit */
- lua_Number u = luaL_checknumber(L, 1);
- luaL_argcheck(L, (lua_Number)1.0 <= u, 1, "interval is empty");
- lua_pushnumber(L, l_mathop(floor)(r*u) + (lua_Number)(1.0)); /* [1, u] */
+ low = 1;
+ up = luaL_checkinteger(L, 1);
break;
}
case 2: { /* lower and upper limits */
- lua_Number l = luaL_checknumber(L, 1);
- lua_Number u = luaL_checknumber(L, 2);
- luaL_argcheck(L, l <= u, 2, "interval is empty");
- lua_pushnumber(L, l_mathop(floor)(r*(u-l+1)) + l); /* [l, u] */
+ low = luaL_checkinteger(L, 1);
+ up = luaL_checkinteger(L, 2);
break;
}
default: return luaL_error(L, "wrong number of arguments");
}
+ /* random integer in the interval [low, up] */
+ up++; /* change interval to [low, up) */
+ luaL_argcheck(L, up - low > 0, 1, "interval is empty");
+ lua_pushinteger(L, (lua_Integer)(r * (lua_Number)(up - low)) + low);
return 1;
}