String#starts_with?

ruby-talk
1

Has anyone run tests to see what the fastest way to do a
String#starts_with?(otherstring) is? I'll need this in an inner loop,
so it's worth squeezing out the few drops of extra speed.

martin

2

Martin DeMello wrote:

Has anyone run tests to see what the fastest way to do a
String#starts_with?(otherstring) is? I'll need this in an inner loop,
so it's worth squeezing out the few drops of extra speed.

String#index should be the fastest

lopex

3

thanks. any suggestions for #ends_with?

martin

···

On 7/9/06, Marcin Mielżyński <lopx@gazeta.pl> wrote:

Martin DeMello wrote:
> Has anyone run tests to see what the fastest way to do a
> String#starts_with?(otherstring) is? I'll need this in an inner loop,
> so it's worth squeezing out the few drops of extra speed.

String#index should be the fastest

4

Marcin Mielżyński wrote:

String#index should be the fastest

I'm afraid it isn't suitable for this case. String#index searches the whole string when the string doesn't start with the start, which is very bad.

Use String# or a regular expression:

   text = "this is a test"
   search = "this"
   text[0, search.length] == search #=> true

   text =~ /^this/ #=> 0 (true)
   text =~ /^test/ #=> nil (false)

Cheers,
   Robin Stocker

5

Martin DeMello wrote:

thanks. any suggestions for #ends_with?

Yes, two examples:

   "this is a test" =~ /test$/ #=> 10 (true)

   text = "this is a test"
   search = "test"
   text[text.length - search.length, search.length] == search #=> true