What's wrong with php addition calculation?

PHP is a widely used programming language. Many websites and applications use PHP as the back-end language. When developing, you often need to perform addition calculations. However, when some developers perform addition operations, they find that the calculation results are not as expected. Why is this?

First of all, we need to understand the basic principles of addition calculation in PHP. The addition operation in PHP uses the " " symbol, for example:

$a = 1;
$b = 2;
$c = $a + $b; // $c的值为3

Obviously, there is no problem with the addition calculation of the above code. However, in actual applications, some developers will encounter some strange errors when performing addition calculations. For example:

$a = 0.1;
$b = 0.2;
$c = $a + $b; // $c的值为0.30000000000000004

The results of the above code are obviously not as expected because of the precision problem of floating point numbers. In computers, floating point numbers have limited precision and cannot be infinitely close to a certain value. Therefore, for some special floating point numbers, the result of the addition calculation may have some slight errors.

In order to avoid calculation errors caused by floating point number precision issues, some developers use string concatenation to perform addition calculations. For example:

$a = '0.1';
$b = '0.2';
$c = $a . $b; // $c的值为0.3

The results of the above code are as expected. However, this method is not very efficient or elegant enough.

So, is there a better solution? The answer is yes. PHP provides a function for high-precision calculations: bcadd().

bcadd()The usage of the function is very simple, as shown below:

$a = '0.1';
$b = '0.2';
$c = bcadd($a, $b, 1); // $c的值为0.3

The above code uses the bcadd() function to perform addition calculations. The three parameters specify the number of decimal places in the calculation result, which can avoid errors caused by precision issues.

In addition to the bcadd() function, PHP also provides a series of high-precision calculation functions, such as bcsub(), bcmul(), bcdiv(), etc. can meet different computing needs.

In short, it is very important to avoid precision problems when performing addition calculations, otherwise it will cause program errors. The use of high-precision calculation functions can solve this problem well and improve the accuracy and reliability of calculations.

The above is the detailed content of What's wrong with php addition calculation?. For more information, please follow other related articles on the PHP Chinese website!