基本介紹
- 中文名：字元串 參數
- 外文名：create_function
- 套用學科：計算機科學
- 適用領域範圍：計算機
函式說明,函式定義,參數,代碼,實例說明,
函式說明
(PHP 4 >= 4.0.1, PHP 5)
create_function - 創建一個匿名（lambda-style）函式
函式定義
參數
該函式的參數。
代碼
該函式的代碼。
作為一個字元串返回一個獨特的功能名稱，或錯誤返回FALSE。
實例說明
例-1 創建一個create_function（匿名函式）
可以使用此功能，（例如）創建一個在運行時收集的信息功能：
<?php
$newfunc = create_function('$a,$b', 'return "ln($a) + ln($b) = " . log($a * $b);');
echo "New anonymous function: $newfunc\n";
echo $newfunc(2, M_E) . "\n";
// outputs
// New anonymous function: lambda_1
// ln(2) + ln(2.718281828459) = 1.6931471805599
?>
或者，也許有一般處理功能，可套用的操作設定為參數列表：
例-2 製作與create_function（一般處理功能）
<?php
function process($var1, $var2, $farr)
{
foreach ($farr as $f) {
echo $f($var1, $var2) . "\n";
}
}
// create a bunch of math functions
$f1 = 'if ($a >=0) {return "b*a^2 = ".$b*sqrt($a);} else {return false;}';
$f2 = "return \"min(b^2+a, a^2,b) = \".min(\$a*\$a+\$b,\$b*\$b+\$a);";
$f3 = 'if ($a > 0 && $b != 0) {return "ln(a)/b = ".log($a)/$b; } else { return false; }';
$farr = array(
create_function('$x,$y', 'return "some trig: ".(sin($x) + $x*cos($y));'),
create_function('$x,$y', 'return "a hypotenuse: ".sqrt($x*$x + $y*$y);'),
create_function('$a,$b', $f1),
create_function('$a,$b', $f2),
create_function('$a,$b', $f3)
);
echo "\nUsing the first array of anonymous functions\n";
echo "parameters: 2.3445, M_PI\n";
process(2.3445, M_PI, $farr);
// now make a bunch of string processing functions
$garr = array(
create_function('$b,$a', 'if (strncmp($a, $b, 3) == 0) return "** \"$a\" '.
'and \"$b\"\n** Look the same to me! (looking at the first 3 chars)";'),
create_function('$a,$b', '; return "CRCs: " . crc32($a) . " , ".crc32(b);'),
create_function('$a,$b', '; return "similar(a,b) = " . similar_text($a, $b, &$p) . "($p%)";')
);
echo "\nUsing the second array of anonymous functions\n";
process("Twas brilling and the slithy toves", "Twas the night", $garr);
?>
上例將輸出：
Using the first array of anonymous functions
parameters: 2.3445, M_PI
some trig: -1.6291725057799
a hypotenuse: 3.9199852871011
b*a^2 = 4.8103313314525
min(b^2+a, a^2,b) = 8.6382729035898
ln(a/b) = 0.27122299212594
Using the second array of anonymous functions
** "Twas the night" and "Twas brilling and the slithy toves"
** Look the same to me! (looking at the first 3 chars)
CRCs: -725381282 , 1908338681
similar(a,b) = 11(45.833333333333%)
<?php
$av = array("the ", "a ", "that ", "this ");
array_walk($av, create_function('&$v,$k', '$v = $v . "mango";'));
print_r($av);
?>
上例將輸出：
Array
(
[0] => the mango
[1] => a mango
[2] => that mango
[3] => this mango
)
