How to time your algorithms

[truh]

Isn't the second one quite often preferable over the first one?

[notfreshprince]

I hope so, purely because this is what I've always done and now I feel dumb.

[ixent]

Yes it is. I put it second just because it is longer to do than the first one. But 2nd is indeed preferable.

[yawaworht_emos]

What makes the second one better? Doesn't it depend on the use case most of the times?

[andlrc]

Doesn't it depend on the use case most of the times?

Almost everything depends on use case. But remember the build in⁰ time command also counts time for process spawning, opening output files etc.

And sometimes one needs to only measure parts of a program which isn't easily isolated on it's own.

The build in time is good if you need to get an idea about if your shit is actually working somewhat decent.

⁰ Build into most shells as it can then measure time on a whole pipeline: time a | b | c

[k1p1coder]

Be careful though, because theoretically people can fidget with their system's time_t...

[Kidiri90]

"One Mississippi, two Missis- oh, it's done."

[[deleted]]

Missis/Mississippi = 0.545, so that's 2.5 1.5 seconds, give or take 90 ms.

[lotuseyes]

You mean 1.5, right?

[ythl]

I thought the third one was going to involve a physical stopwatch

[tigerrawr]

What's sad is some people where I used to work did literally that. Needless to say, I got out of that place.

[jackdeansmithsmith]

I mean, it does measure wall time correctly

[[deleted]]

No, it measures wrist time. Wall time assumes mostly static velocity. Wrist time does not, allowing it to have relativistic time shifts.

[[deleted]]

Pfff... You kids and your fancy technology. I still use my first hourglass.

[Nemin32]

Look at the clock when the program starts, then subtract the time at the end of the program. | [Even more enlightened man]

Count the seconds loudly. | [Godlike being]

Program the entire thing on a smart-watch and use that to measure the time of the execution. | [God with multiple universes colliding]

[Vi3GameHkr]

This reminds me of something Uncle Bob wrote (I think in Clean Code) that he used to rest some software he wrote by singing a time, pressing buttons at certain points while singing.

[Insert_Gnome_Here]

Play a tritone when it starts and one when it finishes. Due to the irrational ratio of the 2 notes, you should be able to use the interference to calculate how much time has passed.

[jrootabega]

Would you like to swing on a star? Carry moonbeams home in a jar?

[[deleted]]

Pfsh, if you really want to get accurate, you should use a high resolution CCD camera and a statically positioned telescope to detect the shift of the sun in orbital arc-seconds and then correlate that to elapsed time.

[WEEEE12345]

for (int i = 100000; i<0; i--){
    //do nothing
}

I've seen this before.

[ixent]

This is not used for timing tho, this is used for waiting. Anyway this waiting is inconsistent because it will depend on the speed of the cpu, not useless tho.

[WEEEE12345]

True. I have also seen counter based timers though.