PHP语法-该注意的细节

php in_array(mixed $needle, array $haystack[, bool $strict = FALSE] )

注意：一、如果$needle 是字符串，则比较是区分大小写的。

　　二、如果$strict = TRUE 则in_array 会比较$needle 和$haystack 的类型是否一致，不一致，则返回FALSE

 1 //例一、in_array 严格类型检查例子
 2 <?php
 3     $a = array('1.12', 2.16, 3.18);
 4     if(in_array('2.16', $a, true))
 5     {
 6         echo "'2.16' found with strict check
";         
 7     }
 8     if(in_array(3.18, $a, true))
 9     {
10         echo "3.18 found with strict check
";         
11     }
12 ?>
13 //output 3.18 found with struct check
14 //例二、in_array()中用数组作为$needle
15  <?php
16     $a = array(array('p', 'h'), array('j', 'q'), 'o');
17     if(in_array(array('p', 'h'), $a))
18     {
19         echo "'ph' was found
";
20     }
21     if(in_array(array('f', 'i'), $a))
22     {
23         echo "'fi' was found
";
24     }
25     if(in_array('o', $a))
26     {
27         echo "'fi' was found
";
28     }
29  ?>
30 //output 'ph' was found
31              'o' was found
32 
33

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in_array 效率问题探讨

分析暂时无时间做

　　可参考：daiyan_csdn的博客

　　总结就是：isset 效率 > 　array_key_exists > in_array

使用isset来判断数据是否在数组中　

1 //使用array_flip将数组key与value翻转，通过isset判断key是否存在于数组中
2 public static function inArray($items, $array)
3 {
4    $flip_array = array_flip($array);
5     return isset($fiip_array[$items]);
6 }

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