(PECL ds >= 1.0.0)
Ds\Set::sum — Returns the sum of all values in the set.
Returns the sum of all values in the set.
Note:
Arrays and objects are considered equal to zero when calculating the sum.
此函数没有参数。
The sum of all the values in the set as either a float or int depending on the values in the set.
Example #1 Ds\Set::sum() integer example
<?php
$set = new \Ds\Set([1, 2, 3]);
var_dump($set->sum());
?>
以上例程的输出类似于：
int(6)
Example #2 Ds\Set::sum() float example
<?php
$set = new \Ds\Set([1, 2.5, 3]);
var_dump($set->sum());
?>
以上例程的输出类似于：
float(6.5)