PHP floating point array sum error

Under normal circumstances, PHP's floating point array sum is very simple, just use the array_sum() function. However, in some special cases, floating-point array summation errors may occur. This situation is usually caused by floating-point precision issues. So, how to solve the floating point array sum error?

First of all, let’s take a look at the issue of floating point number precision. In computers, floating point numbers are stored in binary form, but there are some decimals that cannot be represented by limited binary numbers. For example, decimals like 0.1 cannot be accurately represented in binary. Therefore, the computer will approximate these decimals that cannot be represented accurately when storing them, which will lead to precision problems with floating point numbers.

If we store a bunch of floating point numbers in an array and then use the array_sum() function to sum them, there may be a precision error, which may be one more or less than one decimal place. Bit. This is because the array_sum() function does not consider the accuracy of floating point numbers when calculating, but directly performs addition operations.

So, how to solve this problem?
One solution is to use the sprintf() function to format the floating point numbers, convert them into strings with the same number of digits, and then perform the sum operation. The sample code is as follows:

 $arr = [0.1, 0.2, 0.3];
 $sum = 0;
 foreach ($arr as $value) {
     $sum += sprintf("%.2f", $value);
 }
 echo $sum; // 0.60

In the code, we use the sprintf() function to convert each floating point number into a string with two decimal places, and then perform the sum operation, so that precision errors can be avoided Problem.

In addition, another solution is to use the BC math library, which can provide higher precision mathematical calculations. The sample code is as follows:

 $arr = [0.1, 0.2, 0.3];
 $sum = 0;
 foreach ($arr as $value) {
     $sum = bcadd($sum, $value, 2);
 }
 echo $sum; // 0.60

In the code, we use the bcadd() function to perform the sum operation of floating point numbers. The bcadd() function can ensure the accuracy of mathematical operations. The third parameter 2 means to retain two decimal places. .

To sum up, when an error occurs when summing PHP floating point arrays, we can use the sprintf() function or the BC math library to solve it. In actual development, we need to choose appropriate solutions according to specific situations to ensure the accuracy and accuracy of calculations.

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