is_scalar()

(PHP 4 >= 4.0.5, PHP 5, PHP 7)

检测变量是否是一个标量

描述

如果给出的变量参数$var是一个标量，is_scalar()返回TRUE，否则返回FALSE。

标量变量是指那些包含了integer、float、string或boolean的变量，而array、object和resource则不是标量。

尽管当前的resource类型是居于整数的，但is_scalar()不会把它们当作是标量，因为资源是抽象数据类型。不能依赖于执行细节，因为它可能会改变。

参见is_bool()、is_numeric()、is_float()、is_int()、is_real()、is_string()、is_object()、is_array()和is_integer()。

Having hunted around the manual, I've not found a clear statement of what makes a type "scalar" (e.g. if some future version of the language introduces a new kind of type, what criterion will decide if it's "scalar"? - that goes beyond just listing what's scalar in the current version.)
In other lanuages, it means "has ordering operators" - i.e. "less than" and friends.
It (-:currently:-) appears to have the same meaning in PHP.

Another warning in response to the previous note:
> just a warning as it appears that an empty value is not a scalar.
That statement is wrong--or, at least, has been fixed with a later revision than the one tested. The following code generated the following output on PHP 4.3.9.
CODE:

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