Warning: Division By Zero Working on PHP and MySQL

问题

I am doing a calculation with an array which is drawn from mysql and the problem is "division by zero" warning

I am running a loop over this statment

$v = (($v - $valuei)/($valuei) * 100); 

Here $v is is changing (let's say from 100 to 150 e.g 100, 101, 102, 103,...,150) and $valuei is the intial value of $v (i.e 100) So, when the calculation will start first output should be zero and I want that zero then why it gives a warning "Division By Zero " and also makes all the "$v" values equal to zero.

回答1:

The warning suggests, that $valuei is, in fact, 0 during one of the runs.

Are you sure, that $valuei is initialized properly? To get rid of the warning, you should add do:

if($valuei != 0) {
    $v = (($v - $valuei)/($valuei) * '100');
}

This way, the warning should disappear.

回答2:

If $valuei is initially set to $v then on the first iteration (x - x) = 0 and thus, you are dividing by zero (or rather, are trying to divide 0 by something, which is a mistake).

Without seeing the rest of the loop I can only speculate, but I suspect the direction you're probably heading for is to start the loop at index '1' instead of '0'.

Also, why multiply by '100' instead of 100?

来源：https://stackoverflow.com/questions/11592602/warning-division-by-zero-working-on-php-and-mysql