How to implement interception and replacement in php

How to implement interception and replacement in php: 1. Implement string interception through the substr function in php and the customized substr_cut method; 2. Implement string replacement through the str_replace function in php.

#The operating environment of this article: Windows 7 system, PHP version 7.1, Dell G3 computer.

1. String interception

<?
  //构造字符串
  $str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  echo "原字符串：".$str."
";
  //按各种方式进行截取
  $str1 = substr($str,5);
  echo "从第5个字符开始取至最后：".$str1."
";
  $str2 = substr($str,9,4);
  echo "从第9个字符开始取4个字符：".$str2."
";
  $str3 = substr($str,-5);
  echo "取倒数5个字符：".$str3."
";
  $str4 = substr($str,-8,4);
  echo "从倒数第8个字符开始向后取4个字符：".$str4."
";
  $str5 = substr($str,-8,-2);
  echo "从倒数第8个字符开始取到倒数第2个字符为止：".$str5."
";
 ?>

Supports mixed Chinese and English interception.

/*
------------------------------------------------------
参数：
$str_cut    需要截断的字符串
$length     允许字符串显示的最大长度
程序功能：截取全角和半角（汉字和英文）混合的字符串以避免乱码
------------------------------------------------------
*/
function substr_cut($str_cut,$length)
{
    if (strlen($str_cut) > $length)
    {
        for($i=0; $i < $length; $i++)
        if (ord($str_cut[$i]) > 128)    $i++;
        $str_cut = substr($str_cut,0,$i)."..";
    }
    return $str_cut;
}
?>

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2. String replacement

str_replace("iwind", "kiki", "i love iwind, iwind said");

will output " i love kiki, kiki said"

str_replace(find,replace,string,count)

find required. Specifies the value to look for.

replace Required. Specifies the value to replace the value in find.

string Required. Specifies the string to be searched for.

count Optional. A variable counting the number of substitutions.

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