匹配可变项方程

Question

I am trying to develop a regular expression to match the following equations:

(Price+10%+100+200)
(Price+20%+200)
(Price+30%)
(Price+100)

(Price-10%-100-200)
(Price-20%-200)
(Price-30%)
(Price-100)

My regex so far is...

/([(])+([P])+([r])+([i])+([c])+([e])+([+]|[-]){1}([\d])+([+]|[-])?([\d])+([%])?([)])/g

..., but it only matches the following equations:

(Price+100+10%)
(Price+100+100)
(Price+200)
(Price-100-10%)
(Price-100-100)
(Price-200)

Can someone help me understand how to make my pattern match the full set of equations provided?

Note: Parentheses and 'Price' are musts in the equations that the pattern must match.

Answer 1

Try this, which matches all the input strings provided in the question:

/\(Price([+-]\d+%?){1,3}\)/g

You can test it in a regex fiddle .

Things to note:

• Only use parentheses where you want to group. Parentheses around single-possibility, fixed-quantity matches (eg ([P]) provide no value.
• Use character classes (opened with [ and closed with ] ) for multiple characters that can match at a position in the pattern (eg [+-] ). Single-possibility character classes (eg [P] ) similarly provide no value.
• Yes, character classes (generally) implicitly escape regex special characters within them (eg ( in [(] vs. equivalent \\( outside a character class), but to just escape regex special characters (ie to match them literally), you are better off not using a character class and just escaping them (eg \\( ) – unless multiple characters should match at a position in the pattern (per the previous point to note).
• The quantifier {1} is (almost) always useless: drop it.
• The quantifier + means "one or more" as you probably know. However, in a series of cases where you used it (ie ([(])+([P])+([r])+([i])+([c])+([e])+ ), it would match many values that I doubt you expect (eg ((((((PPPrriiiicccceeeeee ): basically, don't overuse it. Stop to consider whether you really want to match one or more of the character (class) or group to which + applies in the pattern.
• To match a literal string without any regex special characters like Price , just use the literal string at the appropriate position in the pattern – eg Price in \\(Price .

Answer 2

/\\(Price[+-](\\d)+(%)?([+-]\\d+%?)?([+-]\\d+%?)?\\)/g

可在http://www.regexr.com/上使用

Answer 3

/^[(Price]+\d+\d+([%]|[)])&/i

请您自担风险！