What exactly is the difference between
array_filter. What I could see from documentation is that you could pass a callback function to perform an action on the supplied array. But I don't seem to find any particular difference between them.
Do they perform the same thing?
Can they be used interchangeably?
I would appreciate your help with illustrative example if they are different at all.
array_mapcannot change the values inside input array(s) while
array_walkcan; in particular,
array_mapnever changes its arguments.
array_mapcannot operate with the array keys,
array_mapreturns a new array,
true. Hence, if you don't want to create an array as a result of traversing one array, you should use
array_mapalso can receive an arbitrary number of arrays and it can iterate over them in parallel, while
array_walkoperates only on one.
array_walkcan receive an extra arbitrary parameter to pass to the callback. This mostly irrelevant since PHP 5.3 (when anonymous functions were introduced).
array_maphas the same length as that of the largest input array;
array_walkdoes not return an array but at the same time it cannot alter the number of elements of original array;
array_filterpicks only a subset of the elements of the array according to a filtering function. It does preserve the keys.