在 PHP 中将字符串转换为整数的最快方法
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Fastest way to convert string to integer in PHP
提问by nickf
Using PHP, what's the fastest way to convert a string like this: "123"to an integer?
使用 PHP，将这样的字符串转换为"123"整数的最快方法是什么？
Why is that particular method the fastest? What happens if it gets unexpected input, such as "hello"or an array?
为什么那个特定的方法是最快的？如果它得到意外的输入，例如"hello"或 数组，会发生什么？
回答by nickf
I've just set up a quick benchmarking exercise:
我刚刚设置了一个快速的基准测试练习：
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.
平均而言，调用 intval() 慢两倍半，如果您的输入已经是整数，则差异最大。
I'd be interested to know whythough.
我很想知道为什么。
Update: I've run the tests again, this time with coercion (0 + $var)
更新：我再次运行测试，这次是强制的 (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:
附录：我刚刚遇到了一个稍微出乎意料的行为，您在选择以下方法之一时应该注意：
$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
使用 PHP 5.3.1 测试
回答by Rexxars
I personally feel casting is the prettiest.
我个人觉得选角是最漂亮的。
$iSomeVar = (int) $sSomeOtherVar;
Should a string like 'Hello' be sent, it will be cast to integer 0. For a string such as '22 years old', it will be cast to integer 22. Anything it can't parse to a number becomes 0.
如果发送像“Hello”这样的字符串，它将被转换为整数 0。对于像“22 岁”这样的字符串，它将被转换为整数 22。任何不能解析为数字的内容都将变为 0。
If you really do NEED the speed, I guess the other suggestions here are correct in assuming that coercion is the fastest.
如果你真的需要速度，我想这里的其他建议是正确的，假设强制是最快的。
回答by staticsan
Run a test.
运行测试。
string coerce: 7.42296099663
string cast: 8.05654597282
string fail coerce: 7.14159703255
string fail cast: 7.87444186211
This was a test that ran each scenario 10,000,000 times. :-)
这是一个测试，每个场景运行 10,000,000 次。:-)
Co-ercion is 0 + "123"
强制是 0 + "123"
Casting is (integer)"123"
铸造是 (integer)"123"
I think Co-ercion is a tiny bit faster. Oh, and trying 0 + array('123')is a fatal error in PHP. You might want your code to check the type of the supplied value.
我认为强制转换要快一点。哦，尝试0 + array('123')是 PHP 中的一个致命错误。您可能希望您的代码检查所提供值的类型。
My test code is below.
我的测试代码如下。
function test_string_coerce($s) {
return 0 + $s;
}
function test_string_cast($s) {
return (integer)$s;
}
$iter = 10000000;
print "-- running each text $iter times.\n";
// string co-erce
$string_coerce = new Timer;
$string_coerce->Start();
print "String Coerce test\n";
for( $i = 0; $i < $iter ; $i++ ) {
test_string_coerce('123');
}
$string_coerce->Stop();
// string cast
$string_cast = new Timer;
$string_cast->Start();
print "String Cast test\n";
for( $i = 0; $i < $iter ; $i++ ) {
test_string_cast('123');
}
$string_cast->Stop();
// string co-erce fail.
$string_coerce_fail = new Timer;
$string_coerce_fail->Start();
print "String Coerce fail test\n";
for( $i = 0; $i < $iter ; $i++ ) {
test_string_coerce('hello');
}
$string_coerce_fail->Stop();
// string cast fail
$string_cast_fail = new Timer;
$string_cast_fail->Start();
print "String Cast fail test\n";
for( $i = 0; $i < $iter ; $i++ ) {
test_string_cast('hello');
}
$string_cast_fail->Stop();
// -----------------
print "\n";
print "string coerce: ".$string_coerce->Elapsed()."\n";
print "string cast: ".$string_cast->Elapsed()."\n";
print "string fail coerce: ".$string_coerce_fail->Elapsed()."\n";
print "string fail cast: ".$string_cast_fail->Elapsed()."\n";
class Timer {
var $ticking = null;
var $started_at = false;
var $elapsed = 0;
function Timer() {
$this->ticking = null;
}
function Start() {
$this->ticking = true;
$this->started_at = microtime(TRUE);
}
function Stop() {
if( $this->ticking )
$this->elapsed = microtime(TRUE) - $this->started_at;
$this->ticking = false;
}
function Elapsed() {
switch( $this->ticking ) {
case true: return "Still Running";
case false: return $this->elapsed;
case null: return "Not Started";
}
}
}
回答by Nishchit Dhanani
You can simply convert long string into integer by using FLOAT
您可以使用 FLOAT 简单地将长字符串转换为整数
$float = (float)$num;
$float = (float)$num;
Or if you want integer not floating val then go with
或者，如果您想要整数而不是浮动 val，那么请使用
$float = (int)$num;
$float = (int)$num;
For ex.
例如。
(int) "1212.3" = 1212
(float) "1212.3" = 1212.3
回答by Developer
integer excract from any string
从任何字符串中提取整数
$in = 'tel.123-12-33';
$in = 'tel.123-12-33';
preg_match_all('!\d+!', $in, $matches);
$out = (int)implode('', $matches[0]);
//$out ='1231233';
//$out ='1231233';
回答by Elric Wamugu
$int = settype("100", "integer"); //convert the numeric string to int
回答by Andrew Plank
Ran a benchmark, and it turns out the fastest way of getting a realinteger (using all the available methods) is
运行一个基准测试，结果证明获得一个实数的最快方法（使用所有可用的方法）是
$foo = (int)+"12.345";
Just using
只是使用
$foo = +"12.345";
returns a float.
返回一个浮点数。
回答by Daniel
More ad-hoc benchmark results:
更多临时基准测试结果：
$ time php -r 'for ($x = 0;$x < 999999999; $x++){$i = (integer) "-11";}'
real 2m10.397s
user 2m10.220s
sys 0m0.025s
$ time php -r 'for ($x = 0;$x < 999999999; $x++){$i += "-11";}'
real 2m1.724s
user 2m1.635s
sys 0m0.009s
$ time php -r 'for ($x = 0;$x < 999999999; $x++){$i = + "-11";}'
real 1m21.000s
user 1m20.964s
sys 0m0.007s
