How to match a string line by line in php regex?

Question

I have string with multiple newlines, each new line contains a new substring.

Here is an example of the string with 2 lines :

 $x="Hello
       World!

You can see Hello is in the first line and World! is in a newline.

Each substrings start and end with or without a newline(s)|space(s).

I want to match both lines.

My currunt code matched the second line and ignored the first.

 if(preg_match_all("/^\n*\s*(Hello|World!)\s*$/i",$x,$m))

 {print_r($m);}

Is there any way to fix this,so that both lines can be matched?

Your code shouldn't be matching anything. Are you sure that it matches the second line? — Tim Pietzcker
– Tim Pietzcker, Commented Dec 11, 2015 at 6:39
This shouldn't be happening if x indeed is a single string with two words separated by a newline. The alternation allows for only one of the words to match, and the anchors that tie the match to the start and end of the string are outside of the alternation, which means both must match for the regex to succeed - and that means that the string can only match if there is exactly one word in it . If you had used the /m modifier, they would also have matched at the start/end of each new line, but that modifier isn't being used... — Tim Pietzcker
– Tim Pietzcker, Commented Dec 11, 2015 at 6:55

JustOnUnderMillions · Accepted Answer · 2015-12-11 06:41:54Z

1

if(preg_match_all("/(Hello|World!)/i",$x,$m))
{
 print_r($m);
}

If you user ^ $ it matches only the full line. So the Hello part has no \n*\s* before Hello so it won't match. If you change the script like above, it will only lookup for the words, reagless of having any stuff before or after the word.

Hope that helps.

answered Dec 11, 2015 at 6:41

JustOnUnderMillions

3,80511 silver badges14 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Abdulla Nilam · Accepted Answer · 2015-12-11 06:45:19Z

1

Try this

 $x="Hello    
 world! ";

preg_match_all("#\b(Hello|World!)\b#",$x,$m) ;

echo count($m)

Output

Phpfiddle Preview

answered Dec 11, 2015 at 6:45

Abdulla Nilam

39.7k18 gold badges85 silver badges115 bronze badges

Comments

Ryan Cook · Accepted Answer · 2015-12-11 06:47:52Z

1

I'm not sure what the "goal" is but this regex will match both lines. I changed your Hello|World to (.+?) as it matches any character and so would match variables if you are parsing code.

/^(.+?)[\n,\s,\t]{1,8}(.+?)$/

Here is your example with the new regex, so if I misinterpreted you can see what's going on.

<?php 

 $x="Hello
      World!";

 if(preg_match_all("/^(.+?)[\n,\s,\t]{1,8}(.+?)$/i",$x,$m))

 {print_r($m);}

?>

you'll need to determine what and how many potential characters are between the first and second lines if your parsing more than a single series, and then modify the {1,8} to suit spaces, tabs, newlines, etc...

answered Dec 11, 2015 at 6:47

Ryan Cook

1795 bronze badges

Collectives™ on Stack Overflow

How to match a string line by line in php regex?

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related