What is the function of the round function in PHP?

The round function in PHP is used to round a floating-point number to a specified number of decimal places. It approximates a floating-point number by rounding it to the nearest whole number. The syntax of the round function is as follows:

Round the given value to the specified number of decimal places using the desired rounding mode.

In which $value is the floating-point number to be rounded; $precision is the number of decimal places to be retained, with a default of 0 for rounding to the nearest whole number; $mode is an optional parameter that specifies the rounding method, with a default of PHP_ROUND_HALF_UP for rounding to the nearest integer.

For example, using the round function to round the floating point number 3.14159 to 2 decimal places can be done by calling it like this:

$rounded = round(3.14159, 2);
echo $rounded; // 输出 3.14

In this example, the round function rounds 3.14159 to 2 decimal places, resulting in 3.14.

It is important to note that the round function only works with floating point numbers. For integer parameters, it simply returns the original value. Additionally, in PHP, the round function can also be used for rounding negative numbers, and the specific rounding method can be controlled by the $mode parameter.