I have a database call and I’m trying to figure out what the $key => $value does in a foreach loop.
The reason I ask is because both these codes output the same thing, so I’m trying to understand why it’s written this way. Here’s the code:
1)In foreach use $key => $value
foreach($featured as $key => $value){
echo $value['name'];
}
this outputs the same as:
2)In foreach use only $value
foreach($featured as $value) {
echo $value['name'];
}
So my question is, what is the difference between $key => $value or just $value in the foreach loop. The array is multidimensional if that makes a difference, I just want to know why to pass $key to $value in the foreach loop.
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Answer
Well, the $key => $value in the foreach loop refers to the key-value pairs in associative arrays, where the key serves as the index to determine the value instead of a number like 0,1,2,… In PHP, associative arrays look like this:
$featured = array('key1' => 'value1', 'key2' => 'value2', etc.);
In the PHP code: $featured is the associative array being looped through, and as $key => $value means that each time the loop runs and selects a key-value pair from the array, it stores the key in the local $key variable to use inside the loop block and the value in the local $value variable. So for our example array above, the foreach loop would reach the first key-value pair, and if you specified as $key => $value, it would store 'key1' in the $key variable and 'value1' in the $value variable.
Since you don’t use the $key variable inside your loop block, adding it or removing it doesn’t change the output of the loop, but it’s best to include the key-value pair to show that it’s an associative array.
Also note that the as $key => $value designation is arbitrary. You could replace that with as $foo => $bar and it would work fine as long as you changed the variable references inside the loop block to the new variables, $foo and $bar. But making them $key and $value helps to keep track of what they mean.