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Marc
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 question about c language Posted: Thu Jul 12, 2007 8:16 am I need to simplify the code if (va>=817) in=0; else if ((va>=750) && (va>760)) in=3; else if ((va>=730) && (va>740)) in=4; else if ((va>=710) && (va>718)) in=5; else if ((va>=685) && (va>695)) in=6; else if ((va>=665) && (va>675)) in=7; else if ((va>=645) && (va>655)) in=8; else... How can I use switch...case in this situation? Thank You

Joined: 07 Sep 2003
Posts: 1639
Location: Cape Cod Mass USA

 Posted: Thu Jul 12, 2007 9:38 am Beware switch statements usually take an int. 817 doesn't fit in a CCS int. I don't know if CCS lets you use something larger than an int._________________The search for better is endless. Instead simply find very good and get the job done.
inservi

Joined: 13 May 2007
Posts: 127

 Posted: Fri Jul 13, 2007 1:34 pm Hello Marc, Is that real code used in your program ? dro._________________in médio virtus
libor

Joined: 14 Dec 2004
Posts: 288
Location: Hungary

 Posted: Sun Jul 15, 2007 3:21 am You made a typo I think, the second > would have been < . To the point: I would use a lookup table and make the quantization in a loop rather then to have that many if elseif-s. declare a const array with the range values, and find the range in a loop the value fits in. This makes the code more maintanable also.
ckielstra

Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands

Posted: Sun Jul 15, 2007 5:55 am

Another problem with the given example code is that there are gaps in between the tested ranges. For example 740 - 750 is not handled while I suspect that's not what the programmer intended.

If there are indeed no gaps intended the test can be simplified as:
 Code: if (va>=817) in=0; else if (va>=750) in=3; else if (va>=730) in=4; else if (va>=710) in=5; else if (va>=685) in=6; else if (va>=665) in=7; else if (va>=645) in=8; else...

 Quote: To the point: I would use a lookup table and make the quantization in a loop rather then to have that many if elseif-s. declare a const array with the range values, and find the range in a loop the value fits in. This makes the code more maintanable also.
A very nice suggestion. The if-else construction will be more memory efficient when only a few ranges have to be detected, lets say up to a maximum of 10 - 15 tests.
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