How to improve efficiency by searching array elements through PHP

1.php in_array method description

php finds whether an array element exists. Generally, thein_arraymethod is used.

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

Parameter description:
needle
The value to be searched. If needle is a string, the comparison is case-sensitive.

haystack
Array used for comparison

strict
If the value of the third parameter strict is TRUE, then in_array( ) The function also checks whether the type of needle is the same as that in haystack

Return value
If needle is found, it returnsTRUE, otherwise it returnsFALSE.

2.Efficiency of finding elements in in_array

When the compared array haystack is large, the efficiency of in_array will be very low

Example: There are 100,000 in_array pairs The array of elements is compared 1000 times

';/** * 获取microtime * @return float */function getMicrotime(){ list($usec, $sec) = explode(' ', microtime()); return (float)$usec + (float)$sec; }?>

run time:2003.6449432373ms

Usein_arrayto determine whether the element exists, in 100,000 Comparing an array of elements 1000 times, the running time takes about2 seconds

3. Method to improve the efficiency of finding elements

We can usearray_flip## first #Exchange key values, and then use theissetmethod to determine whether the element exists, which can improve efficiency.

Example: Use array_flip to perform key-value exchange first, then use the isset method to judge, and compare 1000 times in an array of 100,000 elements

';/** * 获取microtime * @return float */function getMicrotime(){ list($usec, $sec) = explode(' ', microtime()); return (float)$usec + (float)$sec; }?>

run time:

1.2781620025635ms

Use

array_flipandissetto determine whether an element exists. Compare 1000 times in an array of 100,000 elements. The running time is About1.2 milliseconds
Therefore, for comparison of large arrays, using thearray_flipandissetmethods will be more efficient thanin_arrayMuch higher.

This article explains how to improve the efficiency of searching array elements through PHP. For more related content, please pay attention to the PHP Chinese website.

Related recommendations:

Explanation on mysql strict mode Strict Mode

php uses explode to split strings, problems that novices easily overlook Explanation

Explanation on the two column data method in the mysql exchange table

The above is the detailed content of How to improve efficiency by searching array elements through PHP. For more information, please follow other related articles on the PHP Chinese website!