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Re: cpu times [message #13486 is a reply to message #13485]

Sat, 12 May 2012 11:14

Felix Boehmer
Messages: 149
Registered: May 2007
Location: Munich

first-grade participant

From: *adsl.alicedsl.de

Dear Gianluigi,

while these are interesting measurements, I have to re-cite one those fun meetings we had last summer: You are comparing apples with pears!

If you want to compare the raw performance of the two data classes, you have to use similar functionality, e.g. the [] operator of the <vector> which does no implicit range check. It is unnecessary and bad practice to use at() in loops of the kind

for(int i=0; i<vector.size(); i++) {
meh = vector.at(i); //Completely unnecessary range-check
}

over vectors anyway.

It would be interesting to directly compare assignment and reading performance like you did by replacing at() with []. Another thing you could look at which would have some real-world relevance is to compare array[] and (*<vector-pointer>)[] performance, that is the combined performance of a necessary de-referencing with following raw access.

Cheers

Felix

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[Message index]

		cpu times By: Gianluigi Boca on Fri, 11 May 2012 18:36
		Re: cpu times By: Ralf Kliemt on Sat, 12 May 2012 09:36
		Re: cpu times By: Felix Boehmer on Sat, 12 May 2012 11:14
		Re: cpu times By: Gianluigi Boca on Thu, 31 May 2012 21:20
		Re: cpu times By: Mohammad Al-Turany on Fri, 01 June 2012 11:15

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