php.md

title	description
Floating-point cheat sheet for PHP	Tips for using floating-point and decimal numbers in PHP

Floating-Point Types

PHP is dynamically typed and will often convert implicitly between strings and floating-point numbers (which are platform-dependant, but typically IEEE 64 bit values). To force a value to floating-point, evaluate it in a numerical context:

	$foo = 0 + "10.5"; 

Decimal Types

The BC Math extension implements arbitrary-precision decimal math:

	$a = '0.1';
	$b = '0.2';
	echo bcadd($a, $b);     // prints 0.3

How to Round

Rounding can be done with the number_format() function:

	$number = 4.123;
	echo number_format($number, 2); // prints 4.12

Resources

• PHP manual
  • Floating point types
  • BC Math extension
  • number_format()

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title: 为 PHP 准备的浮点小抄 description: Tips for using floating-point and decimal numbers in PHP

Floating-Point Types

PHP 是动态类型的，它经常暗地里在字符串和浮点数（它们是平台相关的，但典型的是 IEEE 64 位值）之间转换。为了强制一个值为浮点类型，可以在数字上下文中使用：

	$foo = 0 + "10.5"; 

小数类型

BC Math 扩展实现了arbitrary-precision 小数数学：

	$a = '0.1';
	$b = '0.2';
	echo bcadd($a, $b);     // 打印 0.3

如何取整

取整可以用 number_format() 函数完成：

	$number = 4.123;
	echo number_format($number, 2); // 打印 4.12

资源

• PHP 手册
  • 浮点类型
  • BC Math 扩展
  • number_format()