How to Get a Substring from Position N to the Last Char in Ruby

How can I get a substring from position N to the last char in Ruby?

Just slice the string like:

string[N..-1]

Ruby idiom for substring from index until end of string

I think it isn't.

It seems that Range is better way to do it.

Extracting the last n characters from a ruby string

Here you have a one liner, you can put a number greater than the size of the string:

"123".split(//).last(5).to_s

For ruby 1.9+

"123".split(//).last(5).join("").to_s

For ruby 2.0+, join returns a string

"123".split(//).last(5).join

Get last character in string

UPDATE:
I keep getting constant up votes on this, hence the edit. Using [-1, 1] is correct, however a better looking solution would be using just [-1]. Check Oleg Pischicov's answer.

line[-1]
# => "c"

Original Answer

In ruby you can use [-1, 1] to get last char of a string. Here:

line = "abc;"
# => "abc;"
line[-1, 1]
# => ";"

teststr = "some text"
# => "some text"
teststr[-1, 1]
# => "t"

Explanation:
Strings can take a negative index, which count backwards from the end
of the String, and an length of how many characters you want (one in
this example).

Using String#slice as in OP's example: (will work only on ruby 1.9 onwards as explained in Yu Hau's answer)

line.slice(line.length - 1)
# => ";"
teststr.slice(teststr.length - 1)
# => "t"

Let's go nuts!!!

teststr.split('').last
# => "t"
teststr.split(//)[-1]
# => "t"
teststr.chars.last
# => "t"
teststr.scan(/.$/)[0]
# => "t"
teststr[/.$/]
# => "t"
teststr[teststr.length-1]
# => "t"

Ruby - How to select some characters from string

Try foo[0...100], any range will do. Ranges can also go negative. It is well explained in the documentation of Ruby.

Getting a substring in Ruby by x number of chars

How about this?

s[0, s.length - 3]

Or this

s[0..-4]

edit

s = "abcdefghi"
puts s[0, s.length - 3]  # => abcdef
puts s[0..-4]            # => abcdef

Find all indices of a substring within a string

The standard hack is:

indices = "Einstein".enum_for(:scan, /(?=in)/).map do
  Regexp.last_match.offset(0).first
end
#=> [1, 6]

Ruby, remove last N characters from a string?

Ruby 2.5+

As of Ruby 2.5 you can use delete_suffix or delete_suffix! to achieve this in a fast and readable manner.

The docs on the methods are here.

If you know what the suffix is, this is idiomatic (and I'd argue, even more readable than other answers here):

'abc123'.delete_suffix('123')     # => "abc"
'abc123'.delete_suffix!('123')    # => "abc"

It's even significantly faster (almost 40% with the bang method) than the top answer. Here's the result of the same benchmark:

                     user     system      total        real
chomp            0.949823   0.001025   0.950848 (  0.951941)
range            1.874237   0.001472   1.875709 (  1.876820)
delete_suffix    0.721699   0.000945   0.722644 (  0.723410)
delete_suffix!   0.650042   0.000714   0.650756 (  0.651332)

I hope this is useful - note the method doesn't currently accept a regex so if you don't know the suffix it's not viable for the time being. However, as the accepted answer (update: at the time of writing) dictates the same, I thought this might be useful to some people.

Get substring after the first = symbol in Ruby

Not exactly .after, but quite close to:

string.partition('=').last

http://www.ruby-doc.org/core-1.9.3/String.html#method-i-partition

Select all characters in a string until a specific character Ruby

You can avoid creating an unnecessary Array (like Array#split) or using a Regex (like Array#gsub) by using.

a = "2.452811139617034,42.10874821716908|3.132087902867818,42.028314077306646|-0.07934861041448178,41.647538468746916|-0.07948265046522918,41.64754863599606"

a[0,a.index('|')]
#=>"2.452811139617034,42.1087482171"

This means select characters at positions 0 up to the index of the first pipe (|). Technically speaking it is start at position 0 and select the length of n where n is the index of the pipe character which works in this case because ruby uses 0 based indexing.

As @CarySwoveland astutely pointed out the string may not contain a pipe in which case my solution would need to change to

#to return entire string
a[0,a.index('|') || a.size]
# or
b = a.index(?|) ? a[0,b] : a
# or to return empty string
a[0,a.index('|').to_i]
# or to return nil
a[0,a.index(?|) || -1]

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