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"PHP Basics" output approximate value of PI

2022-07-29 03:05:00 【Go home at night】

Functional requirements

The representation of floating-point numbers , Use four methods to output PI （π=3.1415926） Approximate value ：① Use pi() function ;② Use M_PI Constant ;③ Use standard format ;④ Use scientific counting .

The sample code 

<!doctype html>

<html>

<head>

<meta charset="utf-8">

<title> Output the approximate value of PI </title>

</head>



<body>

<?php

  echo ' PI 4 Writing methods ：<p>';

  echo ' The first one is ：pi() = '. pi() .'<br />'; #  Use pi() function 

  echo ' The second kind ：M_PI = '.M_PI.'<br />'; #  Use a constant M_PI

  echo ' The third kind of ：3.14159265359 = '. 3.14159265359 .'<br />'; #  A standard format 

  echo ' A fourth ：314159265359E-11 = '. 314159265359E-11 .'<br />'; #  Scientific enumeration 

?>

</body>

Running results

 

 

Knowledge description

Floating point data types are also known as floating point numbers 、 A double or real number , It can be used to store numbers , You can also save decimals . It provides much greater precision than integers . Floating point data has two writing formats by default ：

One is standard format ：

3.1415

-35.8

One is the format of scientific counting ：

3.58E1

849.72E-3

Be careful ： Floating point numbers are only an approximation , So try to avoid comparing sizes between floating-point numbers , Because the final result is inaccurate .

pi()： It's a function , Return the PI PI Approximate value .

M_PI： Is a constant , Show pi PI Approximate value .

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https://yzsam.com/2022/210/202207290258005296.html

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