Simple Regex syntax for validation!

In software development the Regex is popuplar and the easiest way in validation writing. But It's difficult to remember regex syntax, so this is a some rules to remember it.

• The best way to remember regex syntax is by remembering three things Bracket, caret and Dollars.
• Bracket:
• "[" Square brackets: specify the character which needs to be matched.
• "{" Curly brackets: specify how many character.
• "(" Round brackets: grouping.
• Caret: "^" start a regular expression
• Dollars: "$" end of a regular expression

                Example:   ^[a-z](1,2)$

• The above regex pattern will only take characters which lies between ‘a’ to ‘z’. The same is marked with square bracket to define the range.
• The round bracket indicates the minimum and maximum length.
• Finally caret sign at the start of regex pattern and dollar at the end of regex pattern specifies the start and end of the pattern to make the validation more rigid.
• Enter characters between [a-g] with length of 3?
• [a-g]{3}
• Enter characters between [a-g] with maximum 3 characters and minimum 1 character?
• [a-g]{1,3}
• How can I validate data with 8 digit fix numeric format like 91230456, 01237648 etc?
• ^[0-9]{8}$
• A string with first 3 characters alphabets case insensitive and remaining 8 length numeric?
• ^[a-zA-Z]{3}[0-9]{7}$
• Can we see a simple validation for website URL’s?
• ^www[.][a-z]{1,15}[.](com|net|org)$
• The same for email validation
• ^[a-zA-Z0-9]{1,10}@[a-zA-Z]{1,10}.(com|net|org)$