# =~ vs match - Some benchmarks

**URL:** <https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941>\
**Category:** Ruby\
**Created:** [December 21, 2005, 12:16am UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941 "2005-12-21T00:16:21Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\
**Post date:** [December 21, 2005, 12:16am UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941/1 "2005-12-21T00:16:21Z")

</div>

While profiling some code I noticed =~, String.match and Regexp.match  
turning up in my hotspots. So here is the results of a little  
benchmarking to resolve which is faster to use…

require ‘benchmark’

n = 3000000  
toad = “frogs”  
regex = /frogs/  
regexo = /frogs/o

line = “as fun as looking for frogs in custard”  
puts “string=’#{line}’”  
puts “regex=#{regex}”

Benchmark.bm(20) do |x|  
x.report(“string=~/frogs/o” ) { for i in 1…n; line =~ /frogs/o ;  
end }  
x.report(“string=~/frogs/” ) { for i in 1…n; line =~ /frogs/ ;  
end }  
x.report(“string=~/#{toad}/o”) { for i in 1…n; line =~ /#{toad}/o;  
end }  
x.report(“string=~regex” ) { for i in 1…n; line =~ regex ;  
end }  
x.report(“regex=~string” ) { for i in 1…n; regex =~ line ;  
end }  
x.report(“string=~regexo” ) { for i in 1…n; line =~ regexo ;  
end }  
x.report(“string=~/#{toad}/” ) { for i in 1…n; line =~ /#{toad}/ ;  
end }  
x.report(“regex.match” ) { for i in 1…n; regex.match(line) ;  
end }  
x.report(“string.match” ) { for i in 1…n; line.match(regex) ;  
end }  
end

Results on a P4 2.66Ghz using ruby-1.8.3…

string=‘as fun as looking for frogs in custard’  
regex=(?-mix:frogs)  
user system total real  
string=~/frogs/o 4.390000 1.170000 5.560000 ( 5.936591)  
string=~/frogs/ 4.390000 1.160000 5.550000 ( 6.922374)  
string=~/#{toad}/o 4.450000 1.130000 5.580000 ( 7.111464)  
string=~regex 4.850000 1.100000 5.950000 ( 8.030837)  
regex=~string 4.690000 1.150000 5.840000 ( 7.055707)  
string=~regexo 5.000000 1.120000 6.120000 ( 6.471198)  
string=~/#{toad}/ 23.750000 1.290000 25.040000 ( 28.654952)  
regex.match 7.180000 1.180000 8.360000 ( 9.444980)  
string.match 7.950000 1.170000 9.120000 ( 9.726876)

Results on same machine, using an “all optimization on” version of  
ruby-1.9 (CVS version)…

string=‘as fun as looking for frogs in custard’  
regex=(?-mix:frogs)  
user system total real  
string=~/frogs/o 1.950000 0.000000 1.950000 ( 2.005067)  
string=~/frogs/ 1.960000 0.010000 1.970000 ( 2.000758)  
string=~/#{toad}/o 2.070000 0.000000 2.070000 ( 2.150130)  
string=~regex 2.120000 0.000000 2.120000 ( 2.199664)  
regex=~string 2.150000 0.000000 2.150000 ( 2.284082)  
string=~regexo 2.230000 0.010000 2.240000 ( 2.337823)  
string=~/#{toad}/ 12.580000 0.040000 12.620000 ( 14.492860)  
regex.match 3.870000 0.010000 3.880000 ( 5.636765)  
string.match 4.800000 0.010000 4.810000 ( 5.903205)

John C. Phone : (64)(3) 358 6639  
Tait Electronics Fax : (64)(3) 359 4632  
PO Box 1645 Christchurch Email : removed\_email\_address@domain.invalid  
New Zealand

Carter’s Clarification of Murphy’s Law.

“Things only ever go right so that they may go more spectacularly wrong  
later.”

From this principle, all of life and physics may be deduced.

---

<div class="post-metadata">

**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\
**Post date:** [December 21, 2005, 1:37am UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941/2 "2005-12-21T01:37:47Z")

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On 12/20/05, John C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> While profiling some code I noticed =~, String.match and Regexp.match  
> turning up in my hotspots. So here is the results of a little  
> benchmarking to resolve which is faster to use…

Huh. Interesting. Why is  
string=~/frogs/o  
faster than:  
string=~/frogs/  
…when there are no substitutions involved?

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**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\
**Post date:** [December 21, 2005, 1:43am UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941/3 "2005-12-21T01:43:48Z")

</div>

On 12/20/05, Wilson B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> On 12/20/05, John C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > While profiling some code I noticed =~, String.match and Regexp.match  
> > turning up in my hotspots. So here is the results of a little  
> > benchmarking to resolve which is faster to use…

Thanks for running these, and posting them. Wonder if there shouldn’t  
be a wiki section for benchmarks.

> Huh. Interesting. Why is  
> string=~/frogs/o  
> faster than:  
> string=~/frogs/  
> …when there are no substitutions involved?

Purely a guess… it’s not checking to see if any substitution is  
needed on further runs, where by default, it checks every time.

---

<div class="post-metadata">

**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\
**Post date:** [December 21, 2005, 4:17am UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941/4 "2005-12-21T04:17:05Z")

</div>

On Wed, 21 Dec 2005, Wilson B. wrote:

> On 12/20/05, John C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > While profiling some code I noticed =~, String.match and Regexp.match  
> > turning up in my hotspots. So here is the results of a little  
> > benchmarking to resolve which is faster to use…
> 
> Huh. Interesting. Why is  
> string=~/frogs/o  
> faster than:  
> string=~/frogs/  
> …when there are no substitutions involved?

I suspect they are the same to within the experimental error. ie. No  
difference.

John C. Phone : (64)(3) 358 6639  
Tait Electronics Fax : (64)(3) 359 4632  
PO Box 1645 Christchurch Email : removed\_email\_address@domain.invalid  
New Zealand

Carter’s Clarification of Murphy’s Law.

“Things only ever go right so that they may go more spectacularly wrong  
later.”

From this principle, all of life and physics may be deduced.

---

<div class="post-metadata">

**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\
**Post date:** [December 21, 2005, 12:39pm UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941/5 "2005-12-21T12:39:12Z")

</div>

John C. wrote:

> While profiling some code I noticed =~, String.match and Regexp.match  
> turning up in my hotspots. So here is the results of a little  
> benchmarking to resolve which is faster to use… {cut}

> string=~regexo 5.000000 1.120000 6.120000 ( 6.471198)  
> string=~/#{toad}/ 23.750000 1.290000 25.040000 ( 28.654952)  
> regex.match 7.180000 1.180000 8.360000 ( 9.444980)  
> string.match 7.950000 1.170000 9.120000 ( 9.726876){cut}

Interesting test, John. 🙂  
My results on a P4 1.8Ghz using ruby-1.8.2 on Linux:

string=‘as fun as looking for frogs in custard’  
regex=(?-mix:frogs)  
user system total real  
string=~/frogs/o 3.650000 0.000000 3.650000 ( 3.683330)  
string=~/frogs/ 3.520000 0.010000 3.530000 ( 3.560874)  
string=~/#{toad}/o 3.520000 0.010000 3.530000 ( 3.612038)  
string=~regex 4.110000 0.000000 4.110000 ( 4.159460)  
regex=~string 3.970000 0.010000 3.980000 ( 4.009281)  
string=~regexo 4.010000 0.010000 4.020000 ( 4.046814)  
string=~/#{toad}/ 29.650000 0.150000 29.800000 ( 30.071113)  
regex.match 6.920000 0.030000 6.950000 ( 7.015763)  
string.match 8.230000 0.210000 8.440000 ( 8.739469)

Antonio

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**Author:** ![amin1426](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@amin1426](https://www.ruby-forum.com/u/amin1426)\
**Post date:** [December 21, 2005, 2:58am UTC](https://www.ruby-forum.com/t/vs-match-some-benchmarks/73941/6 "2005-12-21T02:58:57Z")

</div>

Hi,

At Wed, 21 Dec 2005 09:42:06 +0900,  
Bill G. wrote in [ruby-talk:171822]:

> > Huh. Interesting. Why is  
> > string=~/frogs/o  
> > faster than:  
> > string=~/frogs/  
> > …when there are no substitutions involved?
> 
> Purely a guess… it’s not checking to see if any substitution is  
> needed on further runs, where by default, it checks every time.

No, the check is done at the compilation phase, so Resulted  
ASTs should be equivalent. I guess it’s just an error.