* Regular Expressions interview questions
Top Regular Expressions interview questions and answers
Questions : 1 | What is the mean of Regular Expressions ? What the use of Regular Expressions ? | |
Answers : 1 | Regular Expressions means we can say a pattern that one is an expression thatspecifies a set of strings. And there are lot of great use of these expressions like
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Questions : 2 | What the mean of different symbols like ^, $, * , + , ?, ., {},[]in Regular Expressions | |
Answers : 2 | These symbols ^, $, * , + , ?, ., {},[] are very usefull like
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Questions : 3 | How we list which characters we DON’T want ?How to use backslash character | |
Answer : 3 | We can list which characters we DON’T want so just use a ‘^’ as the first symbol in a bracket expression(i.e., “%[^a-zA-Z]%” matches a string with a character that is not a letter between two percent signs).
“^[a-zA-Z]”: a string that starts with a letter; “[0-9]%”: a string that has a single digit before a percent sign; “,[a-zA-Z0-9]$”: a string that ends in a comma followed by an alphanumeric character.In order to be taken literally, you must escape the characters “^.[$()|*+?{\” with a backslash (‘\’), as they have special meaning. On top of that, you must escape the backslash character itself in PHP3 strings, so, for instance, the regular expression “(\$|¥)[0-9]+” would have the function call: ereg(“(\\$|¥)[0-9]+”, $str) |
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Questions : 4 | How you can validate email id use REG expression | |
Answer : 4 | By using below reg expression we can validate email id^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$“^[_a-z0-9-]+”: start with any underscore or alphanumeric one or more then one alfanumaric word
“(\.[_a-z0-9-]+)*@”:any dot(.) or alphanumeric zero times or more the zero and a @ sign “[a-z0-9-]+”:one or more alphanumeric “(\.[a-z0-9-]+)*”: zero or more dot alphanumeric or -(mins sign) “(\.[a-z]{2,5})$”: End with two to 5 character may use dot (.) in that |
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