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5.2. Identifying Elements of an Array

You can access specific values from an array using the array variable's name, followed by the element's key (sometimes called the index) within square brackets:


The key can be either a string or an integer. String values that are equivalent to integer numbers (without leading zeros) are treated as integers. Thus, $array[3] and $array['3'] reference the same element, but $array['03'] references a different element. Negative numbers are valid keys, and they don't specify positions from the end of the array as they do in Perl.

You don't have to quote single-word strings. For instance, $age['Fred'] is the same as $age[Fred]. However, it's considered good PHP style to always use quotes, because quoteless keys are indistinguishable from constants. When you use a constant as an unquoted index, PHP uses the value of the constant as the index:

echo $array[index];               // retrieves $array[5], not $array['index'];

You must use quotes if you're using interpolation to build the array index:


However, don't quote the key if you're interpolating an array lookup:

// these are wrong
print "Hello, $person['name']";
print "Hello, $person["name"]";
// this is right
print "Hello, $person[name]";

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