Regex to select a certain word followed by a integer or decimal?

user_13096858 0
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I need a regular expression to detect the phrase Figure 1.5: in a given string. Also, I intend on using this expression in a PHP preg_replace() function.

Here are some more examples:

  • ...are given. Figure 2.1: shows that...
  • ...are given. Figure 3: shows that...
  • ...are given. Figure 1.16: shows that...
  • ...are given. Figure 0.4 shows that...
  • ...are given. figure 5.1: shows that...

With my limited Regex knowledge, I was able to create this:

/\wFigure \d*\.?\d*/g

But that doesn't even begin to handle all of the permutations that could occur.

I would appreciate any suggestions that you might have.

php regex
1 Answers

There are several points here:

  • You are using \w at the start, perhaps, as a word boundary. In fact, \w matches a letter, digit or _ and actually requires this char to be at the exact location. However, there is no word char before Figure, so you need to either remove \w or replace with \b.
  • preg_replace replaces all non-overlapping occurrences by default, you do not need the g modifier
  • \d*\.?\d* is fine here, but since you want to match any digits followed with zero or more occurrences of . and digits you can use a more specific pattern like \d+(?:\.\d+)*.

You can use

preg_replace('/Figure \d+(?:\.\d+)*/', '', $string)

See the regex demo.

Details:

  • Figure - a string
  • - a space (replace with \s+ to match any one or more whitespaces, and consider adding u flag after last / if you need to find all Unicode whitespaces)
  • \d+ - one or more digits
  • (?:\.\d+)* - zero or more occurrences of . and one or more digits.
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