In Java language, Regex or Regular Expression is an application programming interface which is used for manipulating, searching, and editing a string. Use of Regular Expression in Java (Java Regex)
There are following scripting and programming languages which use the regular expression: Regular Expression in Different Languages It is used to match one non-word character It is used to match any non-decimal digit. It is used to match one decimal digit, which means from 0 to 9. It is used to match one non-white space character. It is used to match a one white space character. This expression matches those strings which do not contain 5, 6, 7, and 8.Įscape Characters or Character Classes Characters It matches those digits or characters which are not defined in the square bracket. This square bracket only matches the upper-case vowels. This square bracket only matches the small case vowels. It is used to match the string, which is either starts with a small case or upper-case letter. It matches letters of an upper case from A to Z. This expression matches the strings such as: It matches letters of a small case from a to z. Suppose, Ab is an expression which matches only the following string: It matches a character which is not defined in the square bracket. It is used for matching a non-capturing group.Ī(?:nt|pple) is an expression which matches to the following string: It matches p, q, or r, followed by either x or y. Xzr is an expression which matches with the following strings:įollowing strings are matched with this expression: It is used to match any character from a range of characters defined in the square bracket. Mab is an expression which matches with the following string:
It specifies an expression to its left for only x times. This character specifies an expression to its left for 0 or more timesīr* is an expression which gives "B", "Br", "Brr", "Brrr", and so on… This character specifies an expression to its left for 0 (Zero) or 1 (one)times.ĪS? is an expression which gives either " a" or " as", but not "ass". S+ is an expression which gives "s", "ss", " sss", and so on. This character specifies an expression to its left for one or more times. The quantifiers are used in the regular expression for specifying the number of occurrences of a character. Such strings are " Abcx", "mnAb", "mnopAbx4". This expression matches those strings in which 'Ab' is present at least one time. It is used to match the substring 'ab' in the string. Such strings are " Amcx", "mnAr", "mnopAx4". This expression matches those strings in which at least one-time A is present. It is used to match the character 'A' in the string. It is used to escape a special character after this sign in a string. If the character on the left side is matched, then the right side's character is ignored.Ī|b is an expression which gives various strings, but each string contains either a or b. It is used to match a particular character or a group of characters on either side. n.ī.x is an expression that match strings such as "bax", "b9x", "bar". This character is used to match any single character in a string except the line terminator, i.e. R$ is an expression match to a string which ends with r such as " aaabr", "ar", "r", "aannn9r", etc. The $sign is used to match an expression to its left at the end of a string. ^a is an expression match to the string which starts with ' a' such as " aab", "a9c", "apr", "aaaaab", etc. This character is used to match an expression to its right at the start of a string. There are following different type of characters of a regular expression: The pattern defined by the regular expression is applied to the given string or a text from left to right.
It is also used in word processors such as word which helps users for searching the text in a document, and also used in various IDEs. This concept or tool is used in almost all the programming or scripting languages such as PHP, C, C++, Java, Perl, JavaScript, Python, Ruby, and many others. In simple words, you can easily search the pattern and replace them with the matching pattern with the help of regular expression. It is mainly used for searching and manipulating text strings. It is also referred/called as a Rational expression. The regex or regexp or regular expression is a sequence of different characters which describe the particular search pattern. The term Regex stands for Regular expression.
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