关于php：在foreach中获取以前的数组值

get previous array values in foreach

我的阵列：

1	$arr = array("jan","feb","mar","apr","mei","jun","jul","agu","sep","okt","nov","des");

然后我做前臂

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foreach($arr as $ar){
echo $ar;
}

号

将输出jan到des

我的问题是如何在当前键中显示以前的值？

例如，当我到达2月时，我也想显示1月，当我到达7月时，我想显示6月，等等。

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$previousValue = null;
foreach($arr as $ar){
echo $ar;
if($previousValue) {
echo $previousValue;
}
$previousValue = $ar;
}

相关讨论

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foreach ($arr as $key => $ar) {
//check we aren't on jan (otherwise we get $key = -1 which doesn't work)
if ($key != 0) {
//print previous month followed by current month
echo $arr[$key - 1] . '-' . $ar . '<br />';
}
}

//OR, if you want to be able to roll through years then:

$last_key = end(array_keys($arr));
foreach ($arr as $key => $ar) {
//check we aren't on jan
if ($key != 0) {
//print previous month followed by current month
echo $arr[$key - 1] . ' - ' . $ar . '<br />';
} else {
echo $arr[$last_key] . ' - ' . $ar . '<br />';
}
}

。

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reset($array);
while($val=current($array))
{
var_dump($val); // current
var_dump(prev($array)); // previous
next($array); // back to current
next($array); // next
}

有点活力

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$arr = array(
"jan",
"feb",
"mar",
"apr",
"mei",
"jun",
"jul",
"agu",
"sep",
"okt",
"nov",
"des"
);
$arr2 = $arr;
foreach ($arr as $k => $currVal) {
unset($arr2[$k]);
foreach ($arr2 as $k => $v) {
$nextVal = $v;

break;
}
echo"next val:" . $nextVal;
echo"current val:" . $currVal;
}

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foreach($arr as $key => $value){
if ($key > 0) {
echo $arr[$key-1];
}
echo $value;
}

。

看看这个问题和答案。

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for ( $i = 0; $i <count($arr); $i++) {
echo $arr[$i]
if($i > 0){
echo $arr[$i-1]
}
}

。