Question

我已经研究并尝试了很多关于如何在foreach循环中正确调用函数的解决方案，但我仍然遇到错误。以下是详细信息：

    $firstName = "CA";
    $firstNameArr = str_split($firstName);

    foreach ($firstNameArr as $value){

    function getLtr($ltr){

        switch ($ltr) :
           case  "A": return 'The letter is A'; 
           case  "B": return 'The letter is B';
           case  "C": return 'The letter is C';
           default: return 'This is not a valid selection';

        endswitch;
    }   
    echo getLtr($value) . '<br>';
    }

我收到的错误：“无法重新声明getltr（）（先前在...引用的第一行函数中声明）”

感谢您的协助！

Answer 1

你的功能应该在循环之外。

尝试这样的事情：

$firstName = "CA";
$firstNameArr = str_split($firstName);

foreach ($firstNameArr as $value){
    echo getLtr($value).'<br>';
}

function getLtr($ltr){

    switch ($ltr) :
       case  "A": return 'The letter is A'; 
       case  "B": return 'The letter is B';
       case  "C": return 'The letter is C';
       default: return 'This is not a valid selection';

    endswitch;
}

Answer 2

你没有把这个函数放在循环中，你可以在循环中调用它。

$firstName = "CA";
$firstNamesArray = str_split($firstName);

foreach ($firstNamesArray as $value) {
    echo getLetter($value) . '<br>';
}

/**
 * The function should be outside the loop.
 * When it's inside, it's getting redeclared every time the loop iterates.
 */
function getLetter($letter) {
    switch ($letter) :
       case  "A": 
            return 'The letter is A'; 
       case  "B": 
            return 'The letter is B';
       case  "C": 
            return 'The letter is C';
       default: 
            return 'This is not a valid selection';
    endswitch;
}

注意我已经拼写了你的函数名和变量。不要使用这样的缩写。尝试编写自我记录的代码，这意味着函数和变量名称是有意义的，而不是神秘的缩写。

Answer 3

你把这个函数放在foreach循环之外就是函数的整个点：）

$firstName = "CA";
    $firstNameArr = str_split($firstName);

     function getLtr($ltr){

        switch ($ltr) :
           case  "A": return 'The letter is A'; 
           case  "B": return 'The letter is B';
           case  "C": return 'The letter is C';
           default: return 'This is not a valid selection';

        endswitch;
    } 

    foreach ($firstNameArr as $value){


    echo getLtr($value) . '<br>';
    }

如何在Foreach循环中正确构造函数？

3 个答案: