preg_match_all regular expression greedy and non-greedy mode

Greedy matching: Regular expressions generally tend to match to the maximum length, which is the so-called greedy matching.

Non-greedy matching: Just match the result with as few matching characters as possible.

So, let’s put it into practice

Use the number of lines of php preg_match_all

Next we need to take out the two links in the string content

Php code

1.

2. $content='

This is obviously not what we want.

Then, as long as we add one more letter to $play_pattern, we can match the information we need

Php code

1. $play_pattern = '/

The result is

Array
(
[0] => Array
(
[0] => BD
[1] => DVD
)


[1] => Array
(
[0] => /videos /68759vod-play-id-68759-sid-0-pid-1.html
[1] => /videos/68759vod-play-id-68759-sid-0-pid-0.html
)


[2] => Array
(
[0] => BD
[1] => DVD
)


)

The difference between greedy mode and non-greedy mode is so big.

Such an error often occurs when regularizing lists in HTML. Using preg_match_all matches the entire string, but substring matching is ignored. leading to incorrect results.