Let’s learn Regular Expression

                           Let’s learn Regular Expression:

 This is the second post for regular expression

Now let’s discuss it more in learning way.

Secret of learning regular expression 

1.start creating it

2. make mistakes.

3. go back to reading basic or books

4. and re-write it

Means more you write regex and make mistake and rectify them by rewriting it ..would make Regular expression expert.

There are some important factors or expressions we need to use while writing regex. I am going discuss those pointers:

·     Backslash (\)

A backslash “escapes” a character. A backslash provides a bridge between Regular Expressions and plain text.

e.g. I need to write a regex to find /testing?id=123

now we know that ? is regex expression and in this string we need to find ? as plain text.

Here backslash comes in picture.

Regex to capture above string /testing\?id=123

Now notice, I use backslash in front of ? due to which regex now treat ? as plain text instead of regex expression. Which means backslash escape a character

Backslash can be used to turn special regex characters into plain characters.

·     Pipe (|)

The pipe is the simplest of Regular Expressions. It means ‘or’. Notice that the pipe matches everything on either side of it.

e.g Lets say we have a page response and you want match all the occurrences of words named test and devops.  Here we can use pipe expression

test | devops

·      Question Mark (?)

A question mark means, “The last item is optional.”

e. g. we have a page with combination of words “colour” and “color” and we need to create regex to match the occurrence of all such words in the page.

we could create an expression like this:

colou?r: while matching for the words, the question mark before checks

for the at least zero or one occurrence of letter 'u' in the word.

With the above expression, we will be able to match both ‘color’ and ‘colour’ from the page.

I would write more post on this topic , because this has many expressions to use.

To read further please click on this link “Regular Expression 2” & "Regular Expression 3"

Happy Testing!!!