Remove duplicate values from the PHP Array

To remove duplicate values from an array, you can use the foreach method or the array_unique method. The following code uses both methods.

<?php$arrF = array();$arrS = array();$intTotal = 100;$intRand = 10;for($i=0; $i < $intTotal; $i++){$arrF[] = rand(1, $intRand);$arrS[] = rand(1, $intRand);}$arrT = array_merge($arrF, $arrS);$arrRF = array();$intStart = time();foreach($arrT as $v){if(in_array($v, $arrRF)){continue;}else{$arrRF[] = $v;}}$intEnd = time();$intTime = $intEnd-$intStart;echo "With Continue,Spend time:$intTime<br/>";$intStart1 = time();$arrRS = array_unique($arrT);$intEnd2 = time();$intTime2 = $intEnd2-$intStart1;echo "With array_unique function,Spend time:($intTime2)";echo "<pre>";print_r($arrT);print_r($arrRF);print_r($arrRS);echo "</pre>";?>

When $ intTotal is relatively small, for example, the value of $ intRand within 1000 basically does not affect the result, and the execution time of both is similar.

When the value of $ intTotal is greater than 10000 and $ intRand is set to 100, the efficiency of using array_unique is higher than that of foreach loop judgment. $ intRand = 10, the execution time of the two is the same.

Therefore, it can be concluded that when the array capacity is small and it is about 1000 or less, the execution efficiency of the two is almost the same.

When the array capacity is relatively large (the specific value is not tested in detail, you can determine the value if you are interested), as $ intRand increases, array_unique performs better, I don't use the $ intTotal/$ intRand ratio because it doesn't feel proportional, but the larger the ratio, the better the array_unique performance.

To sum up, we recommend that you use array_unuique when filtering array duplicate values. When the array is not large, the efficiency of the two is the same, while the use of array_unique will of course reduce your code by several lines at once, when the array capacity is too large, the function performs better. Why not?