下面提供的代码是我的实际代码的一个抽象。我想使用多个循环将多个数组中的项添加到最终数组中。但我还想多次添加相同的值,因此将所有内容包装在另一个循环中。这听起来很混乱,但我认为代码解释得很好。为什么我只能从一个循环中得到结果?换句话说,为什么$total
只包含6个元素1 - 6,而不是30个元素(1 - 6 5次),就像人们对for循环所期望的那样?
for ($counter = 1; $counter < 5; $counter++) {
$first_arr = array('one', 'two', 'three');
$second_arr = array('four', 'five', 'six');
$total = array();
foreach ($first_arr as $x) {
$total[] = $x;
}
foreach ($second_arr as $x) {
$total[] = $x;
}
}
var_dump($total);
因为您在外循环的每次迭代中都重置$total
。在外部循环之前声明它,你的问题就解决了。
一样:
$total = array();
$first_arr = array('one', 'two', 'three');
$second_arr = array('four', 'five', 'six');
for ($counter = 1; $counter < 5; $counter++) {
// assuming $first_arr and $second_arr have numerical keys
// which they do, in this example
$total = array_merge($total, $first_arr, $second_arr);
}
var_dump($total);
将下一行置于for循环之外
$total = array();
只需做一些更改....它会工作的
for ($counter = 1; $counter < 5; $counter++) {
$first_arr = array('one', 'two', 'three');
$second_arr = array('four', 'five', 'six');
$total = array();
$i = 0;
foreach ($first_arr as $x) {
$total[$i] = $x;
$i++;
}
foreach ($second_arr as $x) {
$total[$i] = $x;
$i++;
}
}
var_dump($total);
这是因为你在循环中声明了数组。每次循环再次开始时,数组被重置为空值,因此最终的循环值显示在result中。
在循环外声明这些,它会正常工作,
$first_arr = array('one', 'two', 'three');
$second_arr = array('four', 'five', 'six');
for ($counter = 1; $counter <= 5; $counter++) {
foreach ($first_arr as $x) {
$total[] = $x;
}
foreach ($second_arr as $x) {
$total[] = $x;
}
}