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This article mainly introduces php how to intercept strings according to utf8 coding rules, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

The code is as follows:

/ *

* function: the function is the same as substr, except that it does not cause garbled code.

* parameters:

* return:

, /

Function utf8_substr ($str, $start, $length=null) {

/ / first intercept normally.

$res = substr ($str, $start, $length)

$strlen = strlen ($str)

/ * then judge whether the 6 bytes of each head and tail are complete (not incomplete) * /

/ / if the parameter start is positive

If ($start > = 0) {

/ / intercept about 6 bytes further

$next_start = $start + $length; / / initial location

$next_len = $next_start + 60? $start-6: 0

$prev_segm = substr ($str, $prev_start, $start-$prev_start)

}

/ / start is negative

Else {

/ / intercept about 6 bytes further

$next_start = $strlen + $start + $length; / / initial location

$next_len = $next_start + 60? $start-6: 0

$prev_segm = substr ($str, $prev_start, $start-$prev_start)

}

/ / determine whether the first 6 bytes conform to utf8 rules

If (preg_match ('@ ^ ([\ x80 -\ xBF] {0Magne5}) [\ xC0-\ xFD]? @', $next_segm, $bytes)) {

If (! empty ($bytes [1])) {

$bytes = $bytes [1]

$res. = $bytes

}

}

/ / determine whether the last 6 bytes conform to utf8 rules

$ord0 = ord ($res [0])

If (128 = $ord0) {

/ / intercept it back and add it in front of the res.

If (preg_match ('@ [\ xC0-\ xFD] [\ x80 -\ xBF] {0 5} $@', $prev_segm, $bytes)) {

If (! empty ($bytes [0])) {

$bytes = $bytes [0]

$res = $bytes. $res

}

}

}

Return $res

}

Test data:

The copy code is as follows:

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