Differences

This shows you the differences between two versions of the page.

--- guides:common_coding_errors_payload_testing [2012/10/09 18:32] – danielrichman
+++ guides:common_coding_errors_payload_testing [2012/10/09 18:54] (current) – [Prime Meridian] danielrichman
@@ Line 91: / Line 91: @@
 <code c>long i2 = labs(lround((lon - i1) * 1000000)); // == 1234</code>
+There's another case to consider. Clearly the idea is to split the float into the an integer and a fraction of an integer (i1 and i2 respectively).
+The intention is the above code is that the integer part will supply the negative sign if required. However, consider -0.7. i1 would be -0, but -0 == 0, and the result would be "0.7". We'll have to handle negative numbers explicitly:
+<code c>snprintf(where, buf_size, "%s%i.%06li", (what < 0 ? "-" : ""), labs(i1), i2);</code>
 ==== Equatorial ====
@@ Line 107: / Line 114: @@
     int i1 = what;
     long i2 = labs(lround((what - i1) * 1000000));
-    snprintf(where, buf_size, "%i.%06li", i1, i2);
+    snprintf(where, buf_size, "%s%i.%06li", (what < 0 ? "-" : ""), labs(i1), i2);
 }