Also, they are limited to scalar strings or undef for the values.
另外,它们的值被限制为标量字符串或undef。
Change the #undef macros to #define and set the variable types to int (see Listing 2).
把 #undef宏改为 #define,把变量类型设置为int(见清单 2)。
If -a is a hash switch, then just hello will create a key of hello with an undef value.
如果- a是一个散列开关,那么hello仅会创建一个带有undef值的hello键。
But if UNDEF appears, it is not defined in that object and must be resolved elsewhere.
但如果出现UNDEF,则它不在那个对象中定义并且必须在其他地方被解析。
If the document_root doesn't have any child nodes, for example, config_node will be set to undef, and the third line of the example will raise an error.
例如,如果document_root没有任何子节点,则将config_node设置成undef,并且该示例的第三行将产生一个错误。
If the document_root doesn't have any child nodes, for example, config_node will be set to undef, and the third line of the example will raise an error.
例如,如果document_root没有任何子节点,则将config_node设置成undef,并且该示例的第三行将产生一个错误。
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