php while 循环中的减法
我想我距离 PHP 新手还很远，但由于某种原因我无法让以下内容工作。我正在尝试使用 PHP while 循环从数字中减去一个值。
代码如下，但它似乎只是减去第一个值。
我显然已经启动了一个 mysql 查询，然后有以下代码：
$scMins = 500;
while($f=mysql_fetch_object($r)){
$duration = $f->duration;
$scRem = ($scMins - $duration);
}
return $scRem;
但它只是不工作。
任何帮助将不胜感激。
谢谢， 缺口
I'd like to think I'm far from a PHP novice, but for some reason I cannot get the following to work. I'm trying to subtract a value from a number using a PHP while loop.
The code is below, but it only seems to be subtracting the first value.
I've obviously initiated a mysql query, and then have the following code:
$scMins = 500;
while($f=mysql_fetch_object($r)){
$duration = $f->duration;
$scRem = ($scMins - $duration);
}
return $scRem;
but its just notn working.
Any help would be MUCH appreciated.
Thanks,
Nick
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评论（3）
您总是从初始值 scMins 中减去
You always subtract from the initial value scMins
$r 是什么？
如果它没有返回任何内容，那么很可能意味着您的循环是错误的。我会检查您的查询是否确实返回了某些内容（或者是否错误），问题很可能就在那里。
What is $r?
If it returns nothing, then it most likely means that your loop is wrong. I'd check if your query actually returns something (or if it errors), the problem most likely lies there.
在 while 循环中，变量 $scRem 在每次迭代时都会被覆盖。尝试一下，
但老实说，目前还不清楚您想要实现什么目标，所以这可能是错误的答案;-)
In your while-loop the variables $scRem gets overwritten at each iteration. Try
But honestly it's not very clear what you are trying to achive, so this may be the wrong answer ;-)