PHP Notes: Instructions for using PHP functions range() round() and list()

PHP Notes: Instructions for using PHP functions range() round() and list()_PHP Tutorial

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Release： 2016-07-21 15:11:01

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一>>

range()函数快速创建数组的简单方法,使用low到high范围的整数值填充数组,函数将返回一个包含次范围内所有整数的数组.形式如下

array range(int low,int high[,int step])

典型用法如下

例子:建立1-6的6个数字的数组(骰子)

$die = range(0,6);

建立0-30所有双数的数组

$even = (0,20,2);//步长为2

这个函数不仅仅可以用作数字,还可以用作字母.

如

$words = range('A','Z');

将建立包含A到Z的的所有字母的数组.此处可以用于生成验证码函数.

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round()函数

这个函数是怕我记混淆了.这个函数和上面的哪个range()是天壤之别.

这个函数的作用是

取浮点数的精度

float round(float var[,int preisin})

典型用法

例: $pi = 3.141592653;

round($pi,4);

echo $pi;

将输出 3.1415

三>>

list()函数

list()函数可以在一次操作中从一个数组内提取多个值.同时为变量赋值.形式如下

void list(mixed)

典型用法

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<br><?php <br><br>$info = array('coffee', 'brown', 'caffeine'); <br><br>// Listing all the variables <BR>list($drink, $color, $power) = $info; <BR>echo "$drink is $color and $power makes it special.n"; <br><br>// Listing some of them <BR>list($drink, , $power) = $info; <BR>echo "$drink has $power.n"; <br><br>// Or let's skip to only the third one <BR>list( , , $power) = $info; <BR>echo "I need $power!n"; <br><br>?> <br>
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 代码如下:

$info = array('coffee', 'brown', 'caffeine'); 

// Listing all the variables 
list($drink, $color, $power) = $info; 
echo "$drink is $color and $power makes it special.n"; 

// Listing some of them 
list($drink, , $power) = $info; 
echo "$drink has $power.n"; 

// Or let's skip to only the third one 
list( , , $power) = $info; 
echo "I need $power!n"; 

?> 