Does PHP Have a "built-in" iterator in a Foreach loop?

Question

I'm using a foreach loop to go through the REQUEST array, as I want to have an easy way to utilize the REQUEST array's keys and values.

However, I also want to have a numerical index of how many times the loop has run, as I'm writing a spreadsheet with PHPExcel, and I want to use the SetCellValue function. I'm thinking something like this:

foreach( $_REQUEST as $key => $value){
    $prettyKeys = ucwords(preg_replace($patt_underscore," ",preg_replace($patt_CC,"_",$key)));
    $prettyVals = ucwords(preg_replace($patt_underscore," ",preg_replace($patt_CC,"_",$value)));
    // Replace CamelCase with Underscores, then replace the underscores with spaces and then capitalize string
    // "example_badUsageOfWhatever" ==> "Example Bad Usage Of Whatever"


    $myExcelSheet->getActiveSheet()->SetCellValue( "A". $built-in-foreach-loop-numerical-index ,$prettyKeys);
    $myExcelSheet->getActiveSheet()->SetCellValue( "B". $built-in-foreach-loop-numerical-index ,$prettyVals);
}

I know I can easily implement something like $c = 0 outsite the foreach and then just increment it each time the loop is run, but is there something cleaner?

Harneen

In a word, no. As in pretty much any language, if you want a counter you have to implement it yourself. – Lyford

Use for loop if you need this functionality. – Centimeter

Answer 1

PHP's foreach does not have this functionality built in (per the manual). Use a for loop to have an iterator or implement it yourself.

Ganoid

Answer 2

The for loop will give you an automatic counter, but no way to cycle through your $_REQUEST associative array. The foreach loop will let you cycle through, but without a built-in counter. It's a tradeoff, but at least it's a very manageable one (only takes 2 lines of code to build the counter)!

Orangy

Answer 3

No, there is no built-in iterator numerical index. You can solve this problem in other ways, though.

The most obvious way to do this is using a simple for loop:

for ($i = 0, $numFoo = count($foo); $i < $numFoo; ++$i) {
    // ...
}

You can also use foreach with a counter variable:

$i = 0;
foreach ($foo as $key => $value) {
    // ...
    ++$i;
}

Salubrious

Answer 4

Use the SPL Iterator Class. I'm sure there is something in there you can utilize for this.

Morganatic

Do you know of any good resources for learning how to use these? I've never seen that facet of PHP. – Harneen

I never found any, I've used IteratorIterator, LimitIterator and just had to figure it out myself. Go Google crazy, I'm sure it's out there – Morganatic

Answer 5

Using a For-Loop

You definitely can do this with a for-loop, it's just a bit ugly:

reset($array);
for ($i=0; $i<count($array); $i++) {
    // $i is your counter
    // Extract current key and value
    list($key, $value) = array(key($array), current($array));

    // ...body of the loop...

    // Move to the next array element
    next($array);
}

---

Extend ArrayIterator

My preferred way would be to extend ArrayIterator. Add an internal counter, then override next() and rewind() to update the counter. The counter gives the 0-based key of the current array element:

class MyArrayIterator extends ArrayIterator
{
    private $numericKey = 0;

    public function getNumericKey()
    {
        return $this->numericKey;
    }

    public function next()
    {
        $this->numericKey++;
        parent::next();
    }

    public function rewind()
    {
        $this->numericKey = 0;
        parent::rewind();
    }
}

// Example:
$it = new MyArrayIterator(array(
    'string key' =>'string value',
    1 =>'Numeric key value',
));
echo '<pre>';
foreach ($it as $key =>$value) {
    print_r(array(
        'numericKey' =>$it->getNumericKey(),
        'key' =>$key,
        'value' =>$value,
    ));
}

// Output:
// Array
// (
//     [numericKey] => 0
//     [key] => string key
//     [value] => string value
// )
// Array
// (
//     [numericKey] => 1
//     [key] => 1
//     [value] => Numeric key value
// )

Alta

Answer 6

Your question is answered also here: How can I find out how many times a foreach construct loops in PHP, without using a "counter" variable?

Shortly, no. There isn't any easier way.

Breath

Answer 7

You can get the index of each key of $_REQUEST array:

$req_index= array_flip (array_keys($_REQUEST));

Now you have the numerical index of the current element through $req_index[$key], which gives also the number of iterations of the loop:

foreach($_REQUEST as $key => $value){
    $prettyKeys = ucwords(preg_replace($patt_underscore," ",preg_replace($patt_CC,"_",$key)));
    $prettyVals = ucwords(preg_replace($patt_underscore," ",preg_replace($patt_CC,"_",$value)));
    // Replace CamelCase with Underscores, then replace the underscores with spaces and then capitalize string
    // "example_badUsageOfWhatever" ==> "Example Bad Usage Of Whatever"

    //THE NUMERICAL INDEX IS $req_index[$key]
    $myExcelSheet->getActiveSheet()->SetCellValue( "A". $req_index[$key], $prettyKeys);
    $myExcelSheet->getActiveSheet()->SetCellValue( "B". $req_index[$key], $prettyVals);
}

Serpent

Answer 8

You can actually use foreach with combination of array_values() which will give you keys for each element in the array.

For Example:

$colors = ["red", "blue", "green"];

foreach(array_values($colors) as $key => $color) {
    echo "$color $key";
}
/**Output:
red 0
blue 1
green 2*/

Longplaying