note 41955 deleted from function.array-walk by aidan

Note Submitter: shadedecho ---- in response to "phpContrib (A T) esurfers d o t c o m": Your code is basically correct, I have tested it because I needed something very similar, basically to have it traverse the array recursively, calling the callback function only at the leaf-nodes, not on the sub-indexes of the array. However, I'd suggest one thing in particular to your example: the "recursive" call to array_walk() should go ahead and use the same $prefix variable that was passed into test_alter(), rather than manually specifying 'fruit'. Like this: function test_alter (&$item1, $key, $prefix) { if(is_array($item1)) { array_walk ($item1, 'test_alter', $prefix); // <-- changed return; } $item1 = "$prefix: $item1"; } *************************** Also, though in this example it makes little (if any) sense, and is probably self-obvious to some readers, I wanted to point out for others that you COULD use the same concept for a callback that you DO want to act on each node of an array, instead of only doing an operation on string nodes (like if you were printing out the "type"/"value" of each node in an array, kinda like var_dump() does), whether its string, array, or whatever... you'd simply remove the return statement in the if() construct, and then decide if you want the callback "recursive" call for sub-arrays to happen before or after the processing for that particular node... in other words, to borrow terminology from binary trees, think of the multi-dimensional array as a sort of "unary tree" (only one child per node, instead of 2, or more). In that context, then you decide if you want: 1. a "pre-order traversal" - meaning you process the logic on the node, and THEN call the "recursive" callback if the item happens to itself be a sub-array. This would be a top-down ordering of processing for each branch. function test_alter (&$item1, $key) { /* code block where you put if/switch statements, or any other type (in/)dependent processing logic for the node, such as echo'ing something out like var_dump() does, for instance. */ // now call the "recursive" call back if the node happens // to be a sub-array. if(is_array($item1)) array_walk ($item1, 'test_alter'); } -OR- 2. a "post-order traversal" - means you first call the recursive callback function, which effectively processes any part of the branch "below" the current node FIRST, and THEN you process the current node. This gives a bottom-up ordering of processing for each branch. function test_alter (&$item1, $key) { // first call the "recursive" call back if the node happens // to be a sub-array. if(is_array($item1)) array_walk ($item1, 'test_alter'); // we can be satisified now that all the processing is done // for the part of the branch "below" this node (if there // is any), so now we can process this node. /* code block where you put if/switch statements, or any other type (in/)dependent processing logic for the node. */ }