handle cases with two negative numbers

--  Sasha Mikheev <sasha@avalon-net.co.il>

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@191 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/src/rrd_diff.c b/src/rrd_diff.c
index 3f80a156bd4f2694f83b38d6c0b186328ca54456..c7c11f93a42dc32f61fb7925e48026adab7008eb 100644 (file)
--- a/src/rrd_diff.c
+++ b/src/rrd_diff.c
@@ -7,6 +7,10 @@
  *****************************************************************************
  * $Id$
  * $Log$
+ * Revision 1.4  2003/03/10 00:30:34  oetiker
+ * handle cases with two negative numbers
+ * --  Sasha Mikheev <sasha@avalon-net.co.il>
+ *
  * Revision 1.3  2002/04/01 18:31:22  oetiker
  * "!" takes a higher preference than "||" this means rrd_update N:: would
  * segfault -- Oliver Cook <ollie@uk.clara.net>
@@ -38,21 +42,31 @@ rrd_diff(char *a, char *b)
 {
     char res[LAST_DS_LEN+1], *a1, *b1, *r1, *fix;
     int c,x,m;
-    
-    while (!(isdigit((int)*a) || *a==0))
+    char a_neg=0, b_neg=0;
+    double result;
+   
+    while (!(isdigit((int)*a) || *a==0)) {
+        if(*a=='-') 
+           a_neg = 1;
         a++;
+    }
     fix=a;
     while (isdigit((int)*fix)) 
        fix++;
     *fix = 0; /* maybe there is some non digit data in the string */ 
-    while (!(isdigit((int)*b) || *b==0))
+    while (!(isdigit((int)*b) || *b==0)) {
+       if(*b=='-') 
+           b_neg = 1;  
         b++;
+    }
     fix=b;
     while (isdigit((int)*fix)) 
        fix++;
     *fix = 0; /* maybe there is some non digit data in the string */ 
     if(!isdigit((int)*a) || !isdigit((int)*b))
        return DNAN;
+    if(a_neg+b_neg == 1) /* can not handle numbers with different signs yet */
+       return DNAN;
     a1 = &a[strlen(a)-1];
     m = max(strlen(a),strlen(b));
     if (m > LAST_DS_LEN) return DNAN; /* result string too short */
@@ -93,7 +107,12 @@ rrd_diff(char *a, char *b)
                 c=0;
             }
         }
-        return(-atof(res));
+        result = -atof(res);
     } else
-        return(atof(res));
+        result = atof(res);
+
+    if(a_neg+b_neg==2) /* both are negatives, reverse sign */
+        result = -result;
+    
+    return result;
 }