用於比較兩個變量的PHP函數？

Question

是否有PHP函數用於比較兩個字符串變量與第三個參數是比較運算符和返回布爾值。

實施例：

$string1 = "Foo"; 
$string2 = "Bar"; 
$result = php_function_for_comparing($string1, $string2, "=="); //return boolean 

預先感謝。

Answer 1

要回答我的問題，我創建了一個簡單的函數，而不使用PHP eval（）。

function variable_comparison($condition = "==", $var1, $var2 = false){ 
    if($condition == "is_empty") 
     return empty($var1); 
    else if($condition == "is_filled") 
     return !empty($var1); 
    else if($condition == "==") 
     return $var1 == $var2; 
    else if($condition == "!=") 
     return $var1 != $var2; 
    else if($condition == ">") 
     return $var1 > $var2; 
    else if($condition == "<") 
     return $var1 < $var2; 
    else if($condition == ">=") 
     return $var1 >= $var2; 
    else if($condition == "<=") 
     return $var1 <= $var2; 
    else if($condition == "in_array") 
     return in_array($var1, $var2); 
    else if($condition == "contains") 
     return strpos($var1, $var2); 
    else if($condition == "starts_with") 
     return substr($var1, 0, strlen($var2)) === $var2; 
    else if($condition == "ends_width"){ 
     $length = strlen($var2); 
     return !$length || substr($var1, - $length) === $var2; 
    }  
} 

當您編寫基本條件邏輯並將其保存爲sting時，此函數非常有用。

示例的有條件的邏輯串：

echo ($_POST["foo"] != $_POST["bar"]) ? $_POST["bar"] : "Default Value Here!"; 

但是，當然，你需要創建一個遞歸算法來評估字符串，並將其轉換爲PHP可讀的代碼：

$string_logic = "{if post_[foo]<!=>post_[bar]?post_[bar]:Defalut Value Here!}"; 

爲相同的結果。

Answer 2

那麼，你可能使用eval函數 - 但請注意，eval執行任何PHP代碼傳遞給它。所以你必須正確地驗證給予該方法的任何輸入！

http://php.net/manual/en/function.eval.php

$operator1 = "=="; 
$operator2 = "!="; 

$string1 = "'foo'"; //quote them for evaluation, or you receive syntax errors 
$string2 = "'bar'"; //quote them for evaluation, or you receive syntax errors 

if (eval("return ".$string1 . $operator1 . $string2.";")){ 
    echo "Equal!"; 
} 

if (eval("return ".$string1 . $operator2 . $string2.";")){ 
    echo "Different!"; 
} 

或不引述值之前：

$operator1 = "=="; 
$operator2 = "!="; 

$string1 = "foo"; 
$string2 = "bar"; 

//this passes the strings $string1 and $string2 - which will THEN 
//be evaluated to the values. 
if (eval('return $string1' . $operator1 . '$string2;')){ 
    echo "Equal!"; 
} 

if (eval('return $string1' . $operator2 . '$string2;')){ 
    echo "Different!"; 
} 

Answer 3

呀很多，你可以巧妙與他們使用他們作爲一個布爾

//Calculate the percentage of similarities 
similar_text ($first , $second, $percent) 

levenshtein($str1, $str2) //Calculate Levenshtein distance between two strings 

soundex($str) //Calculate the soundex key of a string 

Answer 4

你可以使用eval。

function compare($a, $b, $op) { 
    return eval('return $a ' . $op . ' $b;'); 
}