php 在PHP中，如何在字符串中调用函数？
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In PHP, How to call function in string?
提问by lovespring
say,string is:
说，字符串是：
$str="abcdefg foo() hijklmopqrst";
How to let php call foo() and insert the return string to this string?
如何让 php 调用 foo() 并将返回字符串插入到这个字符串中？
采纳答案by Basti
$str="abcdefg foo() hijklmopqrst";
function foo() {return "bar";}
$replaced = preg_replace_callback("~([a-z]+)\(\)~",
function ($m){
return $m[1]();
}, $str);
output:
输出：
$replaced == 'abcdefg bar hijklmopqrst';
This will allow any lower-case letters as function name. If you need any other symbols, add them to the pattern, i.e. [a-zA-Z_].
这将允许任何小写字母作为函数名称。如果您需要任何其他符号，请将它们添加到模式中，即[a-zA-Z_].
Be VERYcareful which functions you allow to be called. You should at least check if $m[1] contains a whitelisted function to not allow remote code injection attacks.
要非常小心，它的功能你允许调用。您至少应该检查 $m[1] 是否包含列入白名单的函数以不允许远程代码注入攻击。
$allowedFunctions = array("foo", "bar" /*, ...*/);
$replaced = preg_replace_callback("~([a-z]+)\(\)~",
function ($m) use ($allowedFunctions) {
if (!in_array($m[1], $allowedFunctions))
return $m[0]; // Don't replace and maybe add some errors.
return $m[1]();
}, $str);
Testrun on "abcdefg foo() bat() hijklmopqrst"outputs "abcdefg bar bat() hijklmopqrst".
对"abcdefg foo() bat() hijklmopqrst"输出进行测试运行"abcdefg bar bat() hijklmopqrst"。
Optimisation for whitelisting approach (building pattern dynamically from allowed function names, i.e. (foo|bar).
白名单方法的优化（从允许的函数名称动态构建模式，即(foo|bar).
$allowedFunctions = array("foo", "bar");
$replaced = preg_replace_callback("~(".implode("|",$allowedFunctions).")\(\)~",
function ($m) {
return $m[1]();
}, $str);
回答by HonoredMule
If you're calling a method of some class, you can use normal variable expansion. For example:
如果您正在调用某个类的方法，则可以使用普通的变量扩展。例如：
<?php
class thingie {
public function sayHello() {
return "hello";
}
}
$t = new thingie();
echo "thingie says: {$t->sayHello()}";
This will output:
这将输出：
thingie says: hello
thingie 说： 你好
Note that the braces around the call arerequired.
请注意，调用周围的大括号是必需的。
回答by Frederick Marcoux
Just use this:
只需使用这个：
$str = "abcdefg".foo()."hijklmnopqrstuvwxyz";
It will call function during string creation.
它将在字符串创建期间调用函数。
回答by v.babak
function foo()
{
return 'Hi';
}
$my_foo = 'foo';
echo "{$my_foo()}";
回答by savinger
$foo = foo();
$str = "abcdefg {$foo} hijklmopqrst";
回答by Valerio Bozz
To get arbitrary expressions being evaluated from a double-quoted string you can speculate on variable-functions:
要从双引号字符串计算任意表达式，您可以推测变量函数：
<?php
// A user function
function foo() {
return 'bar';
}
/**
* The hack
*
* @param $v mixed Value
* return mixed Value (untouched)
*/
$_ = function ( $v ) {
return $v;
};
// Happy hacking
echo "Foo is {$_( foo() )} and the sum is {$_( 41 + 1 )}...{$_( str_repeat( ' arrh', 3 ) )}!";
Result:
结果：
Foo is bar and the sum is 42... arrrh arrrh arrrh!
References:
参考：
回答by Mubashar
Its still not possible, There are hacks available but not what I would recommend rather suggest to stick with old school dot operator i.e. $str="abcdefg ". foo() ." hijklmopqrst";
它仍然不可能，有可用的黑客攻击，但不是我推荐的，而是建议坚持使用老式点运算符，即 $str="abcdefg ". foo() ." hijklmopqrst";
As per the Complex (curly) syntax documentation
Note:
Functions, method calls, static class variables, and class constants inside {$} work since PHP 5. However, the value accessed will be interpreted as the name of a variable in the scope in which the string is defined. Using single curly braces ({}) will not work for accessing the return values of functions or methods or the values of class constants or static class variables.
注意：
函数、方法调用、静态类变量和 {$} 中的类常量从 PHP 5 开始工作。但是，访问的值将被解释为定义字符串的范围内的变量名称。使用单花括号 ({}) 不能用于访问函数或方法的返回值或类常量或静态类变量的值。
