Ruby Search and Replace
sub and gsub string methods that use regular expressions, and their in-place variants are sub! and gsub!. The sub & sub! replaces the first occurrence of the pattern and gsub & gsub! replaces all occurrences. All of these methods perform a search-and-replace operation using a Regexp pattern. sub! and gsub! modify the string on which they are called whereas the sub and gsub returns a new string, leaving the original unmodified.
Below is the example to understand it better.
Example :
# Ruby program of sub and gsub method in a string roll = "2004-959-559 # This is Roll Number" # Delete Ruby-style comments roll = roll.sub!(/#.*$/, "") puts "Roll Num : #{roll}" # Remove anything other than digits roll = roll.gsub!(/\D/, "") puts "Roll Num : #{roll}" |
Output :
Roll Num : 2004-959-559 Roll Num : 2004959559
In above example, we are using sub! and gsub!. here sub! replace first occurrence of the pattern and gsub! replaces all occurrences.
Example :
# Ruby program of sub and gsub method text = "Beginner for Beginner, is a computer science portal" # Change "rails" to "Rails" throughout text.gsub!("Beginner", "Beginner") # Capitalize the word "Rails" throughout text.gsub!(/\bBeginner\b/, "Beginner") puts "#{text}" |
Output :
Beginner for Beginner, is a computer science portal
The gsub! method too can be used with a regular expression.