Question

Using PHP, what’s the fastest way to convert a string like this: '123' to an integer?

Why is that particular method the fastest? What happens if it gets unexpected input, such as 'hello' or an array?

Answer 1

I’ve just set up a quick benchmarking exercise:

Function             time to run 1 million iterations -------------------------------------------- (int) '123':                0.55029 intval('123'):              1.0115  (183%)  (int) '0':                  0.42461 intval('0'):                0.95683 (225%)  (int) int:                  0.1502 intval(int):                0.65716 (438%)  (int) array('a', 'b'):      0.91264 intval(array('a', 'b')):    1.47681 (162%)  (int) 'hello':              0.42208 intval('hello'):            0.93678 (222%) 

On average, calling intval() is two and a half times slower, and the difference is the greatest if your input already is an integer.

I’d be interested to know why though.

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Update: I’ve run the tests again, this time with coercion (0 + $var)

| INPUT ($x)      |  (int) $x  |intval($x) |  0 + $x   | |-----------------|------------|-----------|-----------| | '123'           |   0.51541  |  0.96924  |  0.33828  | | '0'             |   0.42723  |  0.97418  |  0.31353  | | 123             |   0.15011  |  0.61690  |  0.15452  | | array('a', 'b') |   0.8893   |  1.45109  |  err!     | | 'hello'         |   0.42618  |  0.88803  |  0.1691   | |-----------------|------------|-----------|-----------| 

Addendum: I’ve just come across a slightly unexpected behaviour which you should be aware of when choosing one of these methods:

$x = '11'; (int) $x;      // int(11) intval($x);    // int(11) $x + 0;        // int(11)  $x = '0x11'; (int) $x;      // int(0) intval($x);    // int(0) $x + 0;        // int(17) !  $x = '011'; (int) $x;      // int(11) intval($x);    // int(11) $x + 0;        // int(11) (not 9) 

_{Tested using PHP 5.3.1}