exp/2196: Wrong arithmetic conversion

abramobagnara@tin.it abramobagnara@tin.it
Wed Nov 8 09:48:00 GMT 2006

>Number:         2196
>Category:       exp
>Synopsis:       Wrong arithmetic conversion
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 08 09:48:01 GMT 2006
>Originator:     abramobagnara@tin.it
>Release:        unknown-1.0

Evaluating comparison expressions the "usual arithmetic conversions" mandated by C standard are not done.

In the cases below note that GDB returns the mathematically correct result, but this is not conforming to C standard and to GDB documentation that says:
"The usual way to examine data in your program is with the `print'
command (abbreviated `p'), or its synonym `inspect'.  It evaluates and
prints the value of an expression of the language your program is
written in"
(GNU gdb Red Hat Linux (
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This GDB was configured as "i386-redhat-linux-gnu"...Using host libthread_db library "/lib/libthread_db.so.1".

(gdb) print (float)123456792.0 > 123456789
$1 = true
(gdb) print (float)123456792.0 > (float)123456789
$2 = false
(gdb) print 123456789123456784.0 == 123456789123456789LL
$3 = false
(gdb) print 123456789123456784.0 == (double)123456789123456789LL
$4 = true


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