Marking the beginning and end of the line in Java

Printer QR in Java Marking the beginning and end of the line

You might want to improve the search, because what you really want is addresses that end with bigCorpcom You can put a special character inside the match string to indicate where the end of the line should be: if (emailmatch(/bigCorpcom$/)){ alert( match ); } else { alert( no match ); } // end if

The dollar sign at the end of the match string indicates that this part of the text should occur at the end of the search string, so andy@bigCorpcom would match, but not bigCorpcom announces a new Web site If you re already an ace with regular expressions, you know this example has a minor problem, but it s pretty picky; I ll explain it in a moment For now, just appreciate that you can include the end of the string as a search parameter Likewise, you can use the caret character (^) to indicate the beginning of a string If you want to ensure that a text field contains only the phrase oogie boogie (and why wouldn t you ), you can tack on the beginning and ending markers /^oogie boogie$/ will only be a true match if there is nothing else in the phrase

In addition to ordinary text, you can use a bunch of special character symbols for more flexible matching

The most powerful character is the period (), which represents a single character Any single character except the newline (\n) will match against the period This may seem silly, but it s actually quite powerful The expression /bg/ will match big, bag, and bug In fact, it will match any phrase that contains b followed by any single character then g, so bxg, b g, and b9g would also be matches

You can specify a list of characters in square braces, and JavaScript will match if any one of those characters matches This list of characters is sometimes called a character class For example, b[aeiou]g will match on bag, beg, big, bog, or bug This is a really quick way to check a lot of potential matches You can also specify a character class with a range For example, the range [a-zA-Z] checks all the letters but no punctuation or numerals

One of the most common tricks is to look for numbers The special character \d represents a number (an integer digit from 0 to 9) You can check for a US phone number (without the area code yet) using this pattern: \d\d\d-\d\d\d\d This looks for three digits, a dash, and four digits

You can tell that regular expressions use a lot of funky characters, like periods and braces What if you re searching for one of these characters Just use a backslash (\) to indicate you re looking for the actual character, not using it as a modifier For example, the e-mail address would be better searched with /bigCorp\com/, because this specifies there must be a period If you don t use the backslash, the regular expression tool interprets the period as any character and would allow something like bigCorpucom Use the backslash trick for most punctuation, like parentheses, braces, periods, and slashes If you want to include an area code with parentheses, just use backslashes to indicate the parentheses: /\(\d\d\d\) \d\d\d-\d\d\d\d/

Sometimes you want to know if something is a word Say you re searching for the word the, but you don t want a false positive on breathe or theater The \b character means the edge of a word, so /\bthe\b/ will match on the but not on words containing the inside them

All the character modifiers refer to one particular character at a time Sometimes you want to deal with several characters at a time There are several operators that help you with this process