在逗号分隔的前缀列表中查找前缀的有效方法

问题描述：

I have a prefix stored in a variable

$prefix = “07”;

And coma separated list of prefixes stored in another variable (the list is provide by user using text box)

$allPrefixes = “07,03,+17”;

What is efficient way to check if the value stored in $prefix is one of the prefixes stored in $allPrefixes

我有一个存储在变量中的前缀 p>

  $前缀 =“07”; 
  code>  pre> 
 
 以逗号分隔的另一个变量中存储的前缀列表（该列表由用户使用文本框提供） p> 
 \  n 
  $ allPrefixes =“07,03，+ 17”; 
  code>  pre> 
 
 检查$ prefix中存储的值是否有效的有效方法是什么？ 存储在$ allPrefixes  p> 
  div>中的一个前缀

答

I'd go for a regex to match:

$regex = "/(^|,)".$prefixe."(,|$)/";
preg_match($regex,$allPrefixes);

On beginning of string before a comma,
between commas or
after comma, at end of string

The above regex will match, for example, 07 but not 007.

General knowledge, not applicable in this case:
If 007 is not likely to appear, or prefixe is not likely to be a substring of any other prefixe, then you can use strpos($allPrefixes, $prefixe) > -1 instead, which is quite more efficient.

However
wrapping the $allPrefixes string between , and using strpos might be both efficient and accurate:

strpos(",".$allPrefixes.",", ",".$prefixe.",")

will match 07 but not 007

在逗号分隔的前缀列表中查找前缀的有效方法

相关推荐