PHP floating point comparison method, php floating point size_PHP tutorial

PHP floating point comparison method, php floating point size

The example in this article describes the PHP floating point comparison method. Share it with everyone for your reference, the details are as follows:

<&#63;php
/**
 * 浮点数一般是不能用来比较大小的，但是我们可以用一种变通的的方式
 * 用var_dump输出浮点是看不出效果的,可以用serialize查看
 * 1.round 2.浮点转换成字符串
 *
 * 转换成字符串方法：
 * 通过在其前面加上(string)或用strval()函数来转变成 字符串
 * 在一个需要字符串的表达式中，字符串会自动转变，比如在使用函数 echo() 或 print() 时， 或在一个变量和一个 字符串 进行比较时，就会发生这种转变
 * true会转为1 ， 而false则会转为空字符串
 *
 */
$a = 13.2;
$b = 24;
$c = $a/$b;
//实际值是这个d:0.54999999999999993338661852249060757458209991455078125;
echo serialize($c).'<br/>';//
echo $c.'<br/>';//输出时会显示成0.55 实际的值是比他小的
//所以直接和0.55比较大小是不成立的
if($c == 0.55){
  echo 'nothing';
}
$c = round($c,2);
//用round处理
if($c == 0.55){
  echo 'ok';
}
echo "<br/>";
//强制转为字符串
// $c = (string)$c;
// $c = strval($c);
if("$c" == 0.55){
  echo 'ok';
}
&#63;>

The running results are as follows:

d:0.54999999999999993338661852249060757458209991455078125;
0.55
ok
ok

Readers who are interested in more PHP-related content can check out the special topics of this site: "Summary of PHP operations and operator usage", "Introduction to PHP basic syntax", "Summary of PHP error and exception handling methods" and "PHP commonly used Summary of functions and techniques》

I hope this article will be helpful to everyone in PHP programming.

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