问题描述
对于SO来说这有点麻烦,因为我不是在试图解决特定的问题,而是只是为了了解如何实现某些问题.但是我追求代码,所以让我们看看它如何运行...
This is slightly OT for SO, because I'm not trying to solve a specific problem, instead just to understand how something might be implemented. But I am after code, so let's see how it goes...
假设我们在一周中的每一天都有一个复选框,并且我们决定将这些复选框的任何组合存储为单个数字,例如:
Let's say we had a checkbox for each day of the week, and we decided to store any combination of those checkboxes as a single number, such that:
0 = no days
1 = Monday
2 = Tuesday
4 = Wednesday
8 = Thursday
16 = Friday
32 = Saturday
64 = Sunday
127 = everyday
如何在PHP中实现该逻辑,以便如果我提交说"13",PHP将只在星期一,星期三和星期四复选框中打勾?
How might one go about implementing that logic in PHP so that if I submitted say, "13", PHP would know to tick only the Monday, Wednesday and Thursday checkboxes?
推荐答案
按位AND
s:
$input = 13;
if( $input & 1 ) {
echo 'Monday';
}
if( $input & 2 ) {
echo 'Tuesday';
}
if( $input & 4 ) {
echo 'Wednesday';
}
// etc
编辑
您可以通过以下方式避免使用if
:
$input = 13;
$days = array('mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun');
for( $i=0; $i<7; $i++ ) {
$daybit = pow(2,$i);
if( $input & $daybit ) {
echo $days[$i] . ' ';
}
}
//output: mon wed thu
除了给这只猫皮上皮以外,还有两种以上的方法,但是最佳"方法取决于您的结果/输出需要什么.
There's more than these two ways to skin this particular cat, but the 'best' way depends on what your result/output needs to be.
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