PHP for loop vs. foreach with range [closed]

Answer 1

comparing execution speed of some php functions

for loop took

for() loop using count() took 20.86401 ms

for() loop Not using count() took 7.09796 ms

using count() means: for ($i = 1; $i < count($myarr); ++ $i) {..

where as foreach() loop:

foreach() took 11.16920 ms

foreach() with KEY took 12.35318 ms

these both are done on same array and their respective execution time is shown both for and foreach are language constructs and their execution speed will be more so you cannot notice much more difference unless you are using them on an array with thousands of records.

Answer 2

Traditional for loop is faster than foreach + range. The first one only uses integer comparison and increasing while the last one has to create an (possibly big) array and then extract each element by moving the internal array cursor and checking whether the end is reached.

If you execute this you can see that plain for is twice faster than foreach + range:

$t0 = microtime(true);
for ($i = 0; $i < 100000; $i++) {
}
echo 'for loop: ' . (microtime(true) - $t0) . ' s', PHP_EOL;

$t0 = microtime(true);
foreach (range(0, 100000) as $i) {
}
echo 'foreach + range loop: ' . (microtime(true) - $t0) . ' s', PHP_EOL;

It is better to use traditional for as a habit in the case you need to iterate a given number of times but at the end of the day you won't see big performance improvements in most scenarios (take into account that the example above iterates 100k times, if you reduce the number of iterations, the difference is smaller).

Answer 3

Foreach is great for iterating through arrays that use keys and values. With for loops, it's more difficult to retain the use of the keys. http://www.c-sharpcorner.com/interviews/answer/2147/ this may be helpful

Answer 4

If it's that critical,

for($i = 0; $i < 1000; ++$i) {}

is faster than

for($i = 0; $i < 1000; $i++) {}

but you'll not really notice much difference over just 1000 iterations

Is it really so essential to micro-optimize.... and if so, why can't you simply set up some test runs to compare the different options yourself

Answer 5

In this particular case (with range() and not an array passed from another scope) - foreach() will be faster. for() would beat it in almost any other case.

Answer 6

Foreach is great for iterating through arrays that use keys and values.

For example, if I had an array called 'User':

$User = array(
    'name' => 'Bob',
    'email' => 'bob@example.com',
    'age' => 200
);

I could iterate through that very easily and still make use of the keys:

foreach ($User as $key => $value) {
    echo $key.' is '.$value.'<br />';
}

This would print out:

name is Bob
email is bob@example.com
age is 200

With for loops, it's more difficult to retain the use of the keys.

When you're using object-oriented practice in PHP, you'll find that you'll be using foreach almost entirely, with for loops only for numerical or list-based things. foreach also prevents you from having to use count($array) to find the total number of elements in the array.