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?

Comments

bill: it's not homework - i'm actually just curious. :)

Written by nickf

Why is "fastest" relevant?

Written by Andy Lester

well if it doesn't hurt (readability), why not do things in the most efficient way possible?

Written by nickf

If it doesn't hurt speed, why not do things in the most readable way possible?

Written by Andy Lester

@Andy, look at the benchmark tests below. The difference between (int) and intval() can be over 400%!

Written by nickf

Accepted Answer

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.


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

Written by nickf
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