array_reduce Iteratively reduce the array to a single value using a callback function mixedarray_reduce arrayinput callbackfunction intinitial array_reduce applies iteratively the function function to the elements of the array input, so as to reduce the array to a single value. If the optional initial is available, it will be used at the beginning of the process, or as a final result in case the array is empty. If the array is empty and initial is not passed, array_reduce returns &null;. ]]> This will result in $b containing 15, $c containing 1200 (= 10*1*2*3*4*5), and $d containing 1. See also array_filter, array_map, array_unique, and array_count_values.