Question

我正在学习如何使用PHP。我将文件内容读入数组并为数组中的每个索引分配变量名。

例如：
$words = file("example.txt"); #each line of the file will have the format a, b, c , d



foreach ($words in $word) {  
$content = explode(",", $word); #split a, b, c, d  
list($a, $b, $c, $d) = $content;  
do something  
}  

/* And now I want to read file, split the sentence and loop over the array again, but
 the last statement will do something else different:   */
foreach ($words in $word) {  
$content = explode(",", $word); #split a, b, c, d  
list($a, $b, $c, $d) = $content;  
do something else different  
}

foreach ($words in $word) { $content = explode(",", $word); #split a, b, c, d list($a, $b, $c, $d) = $content; do something } /* And now I want to read file, split the sentence and loop over the array again, but the last statement will do something else different: */ foreach ($words in $word) { $content = explode(",", $word); #split a, b, c, d list($a, $b, $c, $d) = $content; do something else different } 我该怎么做才能减少这种冗余？正如您所看到的，我无法创建函数，因为最后一个语句对数组执行了不同的操作。但是阅读文件，拆分句子和分配变量的过程是相同的

谢谢

Answer 1

我假设您打算键入foreach($words as $word)，使用“as”而不是“in”，但与问题相比，这只是一个小问题。

您当然可以通过存储explode来电的结果来减少冗余：

$lines = Array();
foreach($words as $word) {
    list($a,$b,$c,$d) = $lines[] = explode(",",$word);
    // do something here
}

foreach($lines as $line) {
    list($a,$b,$c,$d) = $line;
    // do something else
}

这样您就不必再次explode这条线了。

Answer 2

好吧，如果您只是使用$ a，$ b，$ c和$ d工作，并保持$ content完好无损，只需再次列出$ content以做其他不同的事情。

foreach ($words in $word) {  
  $content = explode(",", $word); #split a, b, c, d  

  list($a, $b, $c, $d) = $content;
  // do something, and when you're done:

  list($a, $b, $c, $d) = $content;
  // do something else different.
}

Answer 3

有很多变化。棘手的部分是识别可以抽象出来的通用部分。有时候，通过尝试使代码过于通用，会使代码变得更糟。但这是使用匿名函数的示例。

function foo($filename, $func) {
    $words = file($filename);
    foreach ($words as $word) {
        $content = explode(",", $word);
        call_user_func_array($func, $content);
    }
}

foo('people.txt', function($a, $b, $c, $d) {
    echo "$a\n";
});

foo('people.txt', function($a, $b, $c, $d) {
    echo $b + $c;
});

你可能也对array_map，array_walk和array_reduce感兴趣，虽然我个人认为它们往往不比循环更好... php的foreach非常棒真棒

php foreach循环冗余

3 个答案: