What is optimal algorithm for switch case

[qxoz]

Program receive messages from devices and do some action with result of switch()
Yes it is maybe not so critical but i assume speed is more important.

[andre]

Never assume such things, especially if you are about to sacrifice maintainabiltiy of your code for it.

My first concern is to write code that I (and others) can read and understand later, and can modify if needed later on. Only when profiling shows that a section is time critical, I spend the effort to optimize the design of the code in that area.

[qxoz]

[quote author="Andre" date="1321968332"]Never assume such things, especially if you are about to sacrifice maintainabiltiy of your code for it.

My first concern is to write code that I (and others) can read and understand later, and can modify if needed later on. Only when profiling shows that a section is time critical, I spend the effort to optimize the design of the code in that area. [/quote]

You right. Thank you.
I think i'll use rokemoon's solution.
And thank you everybody for respond and advices

[giesbert]

So,

just some side notes:

switch / case results in a jump (which is fast)

The solution of BilbonSacquet with the arrays result in 3 index based array accesses, which should also be fast.

The solution of rokemoon with the QMap results in a binary search, which should not be too slow, but I assume it slower then the array based access (as it is a search).

But to know, whether that really affects your app and makes it significant slower depends, how often you use it. If it is called 100 times in an msec, it could affect it, if it is called due to user input, forget optimization here. The user is slower ;-)

[qxoz]

[quote author="Gerolf" date="1322037382"]So,

just some side notes:

switch / case results in a jump (which is fast)

The solution of BilbonSacquet with the arrays result in 3 index based array accesses, which should also be fast.

The solution of rokemoon with the QMap results in a binary search, which should not be too slow, but I assume it slower then the array based access (as it is a search).

But to know, whether that really affects your app and makes it significant slower depends, how often you use it. If it is called 100 times in an msec, it could affect it, if it is called due to user input, forget optimization here. The user is slower ;-)[/quote]

Thanks :)

And it's called maximum 10 times per sec.

[rokemoon]

@qxoz
So which solution will you use :-) ?
My question just for information.

[qxoz]

[quote author="rokemoon" date="1322046502"]@qxoz
So which solution will you use :-) ?
My question just for information.
[/quote]

I've already written an algorithm based on yours solution. ;)

[rokemoon]

[quote author="qxoz" date="1322046932"]
I've already written an algorithm based on yours solution. ;)[/quote]
I'm glad to hear it :-)

[giesbert]

[quote author="qxoz" date="1322045941"]And it's called maximum 10 times per sec.[/quote]

Don't care about speed optimization, care about maintainability then :-)

[qxoz]

[quote author="Gerolf" date="1322056043"][quote author="qxoz" date="1322045941"]And it's called maximum 10 times per sec.[/quote]

Don't care about speed optimization, care about maintainability then :-)
[/quote]

I will. Thank you.