How do I search-and-replace strings (not regex) in Ruby?

Question

I have used gsub previously for a regex match, but what should I call for string literals?

I want to replace pair[0] with pair[1] wherever pair[0] is found in the file.

text = File.read( fname )  
@hash_old_to_new.each do
  |pair|
  puts "\tReplacing " + pair[0] + " with " + pair[1]
  # result = text.gsub( /pair[0]/, pair[1] )  <--- this is no good
end
File.open( fname, "w" ) { |file| file << result }

Alex D · Accepted Answer · 2012-11-11 16:34:56Z

6

gsub also works for string literals.

text.gsub!(pair[0], pair[1])

Note that gsub returns a new String, rather than modifying the existing String "in place". Because of the way your code is written, this will cause you to lose updates. You can use gsub!, or else you can chain calls like this:

text = text.gsub(pair[0], pair[1])

answered Nov 11, 2012 at 16:34

Alex D

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Comments

SwiftMango · Accepted Answer · 2012-11-11 16:40:44Z

1

You were not far from the answer:

Directly use string in gsub:

result = text.gsub( pair[0], pair[1] )

Or use a string in regex:

result = text.gsub( /#{pair[0]}/, pair[1] )

answered Nov 11, 2012 at 16:40

SwiftMango

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2 Comments

Dave Newton Over a year ago

No reason to use a literal regex. Not sure how this improves on the existing answer.

SwiftMango Over a year ago

@DaveNewton I am just giving all possible solutions in case someone googled and come in here.

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