问题
I have a simple division:
72 / 193
Excel is giving me result of
0.373056994818653
While PHP round it up to
0.373056994819
My question is - how can I make PHP to give me the exact number instead of a rounded up one?
回答1:
It isn't a question of being 'exact' or not, it is about precision. Wolfram Alpha has a much larger precision for your answer.
You need to change the precision of your php configuration to suit how many units you need after the decimal. I cannot find the largest precision PHP has to offer, but I'm sure there is a limit.
回答2:
The exact number for that is an infinite decimal. You can never get a complete absolute value for that, because that would require infinite memory, something that we sadly do not have access to.
Take a look at bcdiv, which allows for very long ints and floating point numbers
For all practical intents and purposes, however, if two numbers are within 1*10-8 or so, you should be able to consider them equal
You can do this like this:
if(abs($num1-$num2)<=1e-8){
echo "They are equal";
}
来源：https://stackoverflow.com/questions/20244762/php-division-results-in-automatically-rounded-up-number