A regular expression is always contained inbetween slashes, and the matching occurs with "=~" operator. The following expression is true only if the string appears in the variable $sntnce.

We can make use of a conditional for string matching as follows

But it is much easier if we assign the sntnce to the special variable $_ which is a scalar entity. If we follow this then we can avoid making use of match and non-match operators and the above code can simply be written as.

There are many special characters in an RE, and it is these which give them both power and also make them look very complicated. It is better to build your use of REs slowly; their creation can something be of an art form. Here are some of the RE special characters along with their meaning

Here are some of the example matches. Remember that it should be enclosed within /.../ slashes to be used.

To match any one of the characters inside them Square brackets are used. Inside the square brackets a - represents "between" and at the beginning a^ means "not":

"or" is represented by the vertical bar "|" and parentheses (...) are used to group things together:

Here are some more special characters:

Clearly characters such as $, |, [, ), \, / and so on are all peculiar cases in regular expressions. If you want to match any of these then you should preceed it by a backslash as shown below.

It is probably best to build up your use of regular expressions slowly, as was mentioned earlier,. Given below are some examples.