Question

I ran into this code, foreach($vars as $a=>$var){ // some process here} and I wonder what is the difference when using foreach($vars as $var){ // some process here} ? Thanks.

Answer 1

The operator => represents the relationship between a key and value. You can imagine that the key points => to the value.

EDIT:

foreach can be used in two ways:

1.Iterating over values:

Each time round the loop, the variable is set to the next value in the array.

Eg:

$fruitColours = array(
    "Banana" => "Yellow",
    "Apple"  => "Green",
    "Plum"   => "Purple",
);

foreach ($fruitColours as $colour)
{
    echo "$colour<br/>\n";
}

?>

The above will display:

Yellow
Green
Purple

Only the values of the array are displayed.

2.Iterating over keys and values

Each time round the loop, the variables are set to the next key and value pair.

Eg:

$fruitColours = array(
    "Banana" => "Yellow",
    "Apple"  => "Green",
    "Plum"   => "Purple",
);

foreach ($fruitColours as $fruit => $colour)
{
    echo "$fruit is $colour<br/>\n";
}

?>

The above will display:

Banana is Yellow
Apple is Green
Plum is Purple

Check the php foreach documentation for further reference