Differences Preg_match?

Question

I want to ask, what is the meaning or difference between these two lines?

2. if( preg_match_all('/\#([א-תÀ-ÿ一-龥-a-z0-9\-_]{1,50})/iu', $message, $matches, PREG_PATTERN_ORDER) ) {

3. if( preg_match_all('/\#([-a-z0-9\-_\x{4e00}-\x{9fa5}]{1,50})/iu', $message, $matches, PREG_PATTERN_ORDER) ) {

and what does the number 3 on this line mean? (Arrow)

if( preg_match_all('/\@([a-zA-Z0-9\-_\x{4e00}-\x{9fa5}]{->3,30})/u', $message, $matches, PREG_PATTERN_ORDER) ) {

Thank!

Answer 1

I will answer the second part of your question:

{3,30}in regular expression means quantifierfor a minof 3and max 30 repetitions.

• a* means zero or more a
• a+ means one or more a
• a? means zero or one a
• a{1} means exactly the same one as simple a
• a{1,} means one or more of the same as a+
• a{1,3} means min one and max 3 a's

a. : [a-zA-Z]{3,30} 3 30 .

Answer 2

(, , ), 2- .

Answer 3

Unicode Unicode.

\x {FFFF}, FFFF - 1 4
Perl . .

:
\ x {E0} U + 00E0.
\ x {A9} ©

Thus it tries to match every Unicode character from U+4e00 to U+9fa5 (from 一 to 龥) whereas the last one is not a valid Unicode character.

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The first expressions also try to match these characters ( 一-龥), but they are not expressed in Unicode syntax (regardless of whether this contradicts a problem that I don't know). In addition (as already mentioned) the first expression corresponds to a greater number of characters, namely א-תand À-ÿ.

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The second question was already answered very well by unicornaddict.