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Re: cpu times [message #13486 is a reply to message #13485] Sat, 12 May 2012 11:14 Go to previous messageGo to previous message
Felix Boehmer is currently offline  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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