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= Regular Expressions in Ruby vs. Java = | |||
Ruby and Java both support Regular Expressions, but generally speaking, Ruby's dynamic typing and native regular expression support allow for equivalent or similar functions | Ruby and Java both support Regular Expressions, but generally speaking, Ruby's dynamic typing and native regular expression support allow for performing equivalent or similar functions more simply and with less code. | ||
== General Differences == | |||
Ruby can perform most regular expression related functions using a combination of the String and Regexp classes. The String class has several methods that take a Regexp as a parameter, and similarly the Regexp class has methods that take a String as a parameter. Ruby also provides a shorthand for defining regular expressions, a string surrounded by forward slashes: Regexp.new('test') and /test/ are equivalent. | Ruby can perform most regular expression related functions using a combination of the String and Regexp classes. The String class has several methods that take a Regexp as a parameter, and similarly the Regexp class has methods that take a String as a parameter. Ruby also provides a shorthand for defining regular expressions, a string surrounded by forward slashes: Regexp.new('test') and /test/ are equivalent. | ||
Mostly, Java does not have native support for regular expressions. While the String class has a few methods that can perform related functions, they do not necessarily follow the conventional rules of regular expressions. Proper regular expression support is available in Java through several packages, most notably java.util.regex, which is Sun's standard package available in Java 1.4+. This package provides two classes, Pattern and Matcher, which are respectively used to define and operate on regular expressions. These classes work in conjunction with the String class to perform regular expression functions. | Mostly, Java does not have native support for regular expressions. While the String class has a few methods that can perform related functions, they do not necessarily follow the conventional rules of regular expressions. Proper regular expression support is available in Java through several packages, most notably java.util.regex, which is Sun's standard package available in Java 1.4+. This package provides two classes, Pattern and Matcher, which are respectively used to define and operate on regular expressions. These classes work in conjunction with the String class to perform regular expression functions. | ||
== Code Examples == | |||
The following examples will illustrate how Ruby and Java perform the same regular expression task differently. | |||
Find a regular expression match within a string. | |||
In Ruby, there are 2 simple ways to do this, the main difference between them being that one is a String method and one is a Regexp method. | |||
First the String method, the [http://www.ruby-doc.org/core/classes/String.html#M000792 =~] operator, which returns the index in the string at which the pattern first matches. | |||
"This is a string" =~ /is/ | |||
>> 2 | |||
"This is a string" =~ /hello/ | |||
>> nil | |||
An equivalent way to do this is with the Regexp method match(). Note that match() returns a [http://www.ruby-doc.org/core/classes/MatchData.html MatchData] object if successful. | |||
/is/.match("This is a string") | |||
>> #<MatchData:0x5e1715c> | |||
/hello/.match("This is a string") | |||
>> nil | |||
[[CSC/ECE 517 Summer 2008/wiki1 Assignment|Back to the assignment page]] | [[CSC/ECE 517 Summer 2008/wiki1 Assignment|Back to the assignment page]] | ||
Revision as of 12:43, 30 May 2008
Regular Expressions in Ruby vs. Java
Ruby and Java both support Regular Expressions, but generally speaking, Ruby's dynamic typing and native regular expression support allow for performing equivalent or similar functions more simply and with less code.
General Differences
Ruby can perform most regular expression related functions using a combination of the String and Regexp classes. The String class has several methods that take a Regexp as a parameter, and similarly the Regexp class has methods that take a String as a parameter. Ruby also provides a shorthand for defining regular expressions, a string surrounded by forward slashes: Regexp.new('test') and /test/ are equivalent.
Mostly, Java does not have native support for regular expressions. While the String class has a few methods that can perform related functions, they do not necessarily follow the conventional rules of regular expressions. Proper regular expression support is available in Java through several packages, most notably java.util.regex, which is Sun's standard package available in Java 1.4+. This package provides two classes, Pattern and Matcher, which are respectively used to define and operate on regular expressions. These classes work in conjunction with the String class to perform regular expression functions.
Code Examples
The following examples will illustrate how Ruby and Java perform the same regular expression task differently.
Find a regular expression match within a string. In Ruby, there are 2 simple ways to do this, the main difference between them being that one is a String method and one is a Regexp method. First the String method, the =~ operator, which returns the index in the string at which the pattern first matches.
"This is a string" =~ /is/ >> 2 "This is a string" =~ /hello/ >> nil
An equivalent way to do this is with the Regexp method match(). Note that match() returns a MatchData object if successful.
/is/.match("This is a string") >> #<MatchData:0x5e1715c> /hello/.match("This is a string") >> nil