Regular expressions - string substitution

Ruby
#1

Hello all,

A quick question if I have a string like so

000000100

and I want to remove the leading 0’s to leave me with a string like so

100

What is the best way to do this? initially I was using
string.delete(“0”) but that obviously deletes every 0 and is not the
desired outcome. I then though string.gsub(/^0/, “”) however this only
gets rid of the very first 0. Does anyone have any suggestions?

Thanks a lot

#2

“000000100”.to_i.to_s # => 100

#3

So long as you’ll always be converting numbers, you can use to_i. That
will convert the string into an integer.

“000000100”.to_i
=> 100

Keep in mind that it will truncate the number as soon as it reaches a
non-number. For instance:

“00012,345,678”.to_i
=> 12

If you need to keep decimals then you can use to_f. For example:

“0001234.567”.to_f
=> 1234.567

#4

Thanks all. I completely forgot about that. It always the simple things

Marc H. wrote:

“000000100”.to_i.to_s # => 100

#5

On Fri, 4 Sep 2009 23:24:34 +0900
Ne Scripter [email protected] wrote:

string.gsub(/^0/, “”)

Try something like this:

string.gsub(/^0*/, “”)

This means: 0 or more occurrences of character “0”, starting at the
beginning of the string.

#6

Ne Scripter wrote:

Thanks all. I completely forgot about that. It always the simple things

Marc H. wrote:

“000000100”.to_i.to_s # => 100

I then though string.gsub(/^0/, “”) however this only
gets rid of the very first 0.

string.gsub(/^0+/,"")

#7

On Sep 4, 2009, at 9:24 AM, Ne Scripter wrote:

What is the best way to do this? initially I was using
string.delete(“0”) but that obviously deletes every 0 and is not the
desired outcome. I then though string.gsub(/^0/, “”) however this only
gets rid of the very first 0. Does anyone have any suggestions?

“000000100”.sub(/\A0+/, “”)

\A means the beginning of the String and 0+ means one or more zeros.

Also note the use of sub() which only matches once over gsub() which
is used to repeat for all matches. There can only be one run of zeros
at the front of the String, so sub() is all we need.

Hope that helps.

James Edward G. II

#8

Hello,

What is the best way to do this? initially I was using
string.delete(“0”) but that obviously deletes every 0 and is not the
desired outcome. I then though string.gsub(/^0/, “”) however this only
gets rid of the very first 0. Does anyone have any suggestions?

string.sub(/^0+/,’’)

should do what you are looking for.

Cheers,

#9

On Sep 4, 2009, at 10:24 AM, Ne Scripter wrote:

What is the best way to do this? initially I was using
string.delete(“0”) but that obviously deletes every 0 and is not the
desired outcome. I then though string.gsub(/^0/, “”) however this only
gets rid of the very first 0. Does anyone have any suggestions?

Thanks a lot

string.sub(/^0*/,’’)

Or /^0+/ since both work if there are zeroes, but find nothing if the
first character is not a 0.

If your intention is to convert to a number, then one of the other
responses will work, but since you presented a string and asked to be
left with a string, I wanted to be sure you saw this simple tweak to
what you’d already discovered.

-Rob

Rob B. http://agileconsultingllc.com
[email protected]