Explanation of php str_replace method of replacing specified times

php str_replace method, replace the string

The format is as follows:

mixed str_replace ( mixed $search , mixed $replace , mixed $subject [, int &$count ] )

search The target value to search for, which is needle. An array can specify multiple targets.

replace Replacement value for search. An array can be used to specify multiple replacements.

subject Array or string to perform replacement. That is haystack. If subject is an array, the replacement operation will traverse the entire subject and the return value will also be an array.

count If specified, its value will be set to the number of times replacement occurred. That is, how many replacements have occurred in total.

Explanation:

If search and replace are arrays, then str_replace() will do both for the subject. Mapping replacement.

If the number of replace values ​​is less than the number of search values, empty strings will be used for redundant replacements.

If search is an array and replace is a string, then the replacement of each element in search always uses this string.

str_replace replacement method is case-sensitive.

Example:

<?php
$str = &#39;abcdefgh&#39;;
echo str_replace(&#39;abc&#39;, &#39;123&#39;, $str); // 123defgh
$str = &#39;123456&#39;;
$search = array(1, 2, 3, 4, 5, 6);
$replace = array(&#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;, &#39;f&#39;, &#39;g&#39;);
echo str_replace($search, $replace, $str); // abcdefg
$arr = array(&#39;abc&#39;,&#39;bac&#39;,&#39;cba&#39;);
$result = str_replace(&#39;b&#39;, &#39;B&#39;, $arr, $count);
print_r($result); // Array ( [0] => aBc [1] => Bac [2] => cBa )
echo $count;      // 3 共替换了3次
?>

It is more convenient to use str_replace to replace strings, but all values ​​matching search will be Replaced with the value of replace. If you want to replace a specified number of times, this method cannot be implemented.

For example: user_order_list is replaced with user/order_list

<?php
$str = &#39;user_order_list&#39;;
echo str_replace(&#39;_&#39;, &#39;/&#39;, $str); // user/order/list
?>

Replace the specified The method of times can be implemented using the regular preg_replace method.

<?php
/**
 * 对字符串执行指定次数替换
 * @param  Mixed $search   查找目标值
 * @param  Mixed $replace  替换值
 * @param  Mixed $subject  执行替换的字符串／数组
 * @param  Int   $limit    允许替换的次数，默认为-1，不限次数
 * @return Mixed
 */
function str_replace_limit($search, $replace, $subject, $limit=-1){
    if(is_array($search)){
        foreach($search as $k=>$v){
            $search[$k] = &#39;`&#39;. preg_quote($search[$k], &#39;`&#39;). &#39;`&#39;;
        }
    }else{
        $search = &#39;`&#39;. preg_quote($search, &#39;`&#39;). &#39;`&#39;;
    }
    return preg_replace($search, $replace, $subject, $limit);
}
?>

Example:

<?php
$str = &#39;user_order_list&#39;;
echo str_replace_limit(&#39;_&#39;, &#39;/&#39;, $str, 1); // user/order_list
$arr = array(&#39;abbc&#39;,&#39;bbac&#39;,&#39;cbba&#39;);
$result = str_replace_limit(&#39;b&#39;, &#39;B&#39;, $arr, 1);
print_r($result); // Array ( [0] => aBbc [1] => Bbac [2] => cBba )
?>

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