+- MISRA Discussion Forums (https://forum.misra.org.uk)
+-- Forum: MISRA C (https://forum.misra.org.uk/forumdisplay.php?fid=4)
+--- Forum: General Questions (https://forum.misra.org.uk/forumdisplay.php?fid=27)
+--- Thread: Misra rule 42 (/showthread.php?tid=466)
Misra rule 42 - JeroenBoonen - 28-02-2008
Hi,
I have a question concerning rule 42, which states : \"comma operator shall not be used, except in the control expression of a for loop\".
Now what is \"the control expression\" in following instruction : for(i = 0; i < 10; i++) {...}
Is it \"i = 0\" or \"i < 10\" or \"i++\" ?
Currently we use a GreenHills compiler with build-in misra checking and they are saying it is \"i < 10\".
Searching on google:
IAR and ABRAXAS says it is \"i = 0\" and \"i++\"
Now hopefully you can give me the correct answer.
Thank you,
Jeroen
Controlling expression - derek_farn - 28-02-2008
The technical term is actually \"controlling expression\", not \"control expression\".
The wording is here:
http://c0x.coding-guidelines.com/6.8.5.3.html
and the footnote specifying which of the expressions is the controlling expression (the middle one) is here
http://c0x.coding-guidelines.com/6.8.6.html
- JeroenBoonen - 28-02-2008
Hi, many thankx, so greenhills was right.
Anyway, where came this rule from? Because the comma operator is only usefull in the two other expressions, like:
for(i = 0,j = 0; i < 10; i++, j++)
Greetings,
Jeroen