preg_replace

  • We perform pattern based substitution in Ruby using String#gsub, which is equivalent to PHP’s preg_replace function. A notable difference is that the String#gsub method is also used for string substitution in Ruby. We do this by simply providing a string instead of the regular expression pattern. This would be like using the str_replace function in PHP.

    In this example, we want to replace the domain in all emails with foo.

    PHP

    $string = 'joe@example.com; walter@example.org';
$result = preg_replace('/@([a-z0-9-]+)/', '@foo', $string);
 
var_export($result);
// => 'joe@foo.com; walter@foo.org'

    Ruby

    string = 'joe@example.com; walter@example.org'
result = string.gsub(/@([a-z0-9-]+)/, '@foo')
 
p result
# => "joe@foo.com; walter@foo.org"

    We can use backreferences in our gsub replacements just as we would with preg_replace by using \1, \2, etc in our replacement string.

    In this example, we prefix the existing domain with mail.. Remember to escape backslashes used for the backreference.

    PHP

    // Replace domain with mail.domain
$string = 'joe@example.com; walter@example.org';
$result = preg_replace('/@([a-z0-9-]+)/', '@mail.\\1', $string);
 
var_export($result);
// => 'joe@mail.example.com; walter@mail.example.org'

    Ruby

    string = 'joe@example.com; walter@example.org'
result = string.gsub(/@([a-z0-9-]+)/, '@mail.\\1')
 
p result
# => "joe@mail.example.com; walter@mail.example.org"

    see also

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