你理解错了吧,PHP手册的原文是:
Note: PHP will evaluate a non-numeric string as 0 if compared to integer, but still return the string if it's seen as the numerically highest value. If multiple arguments evaluate to 0, max() will return a numeric 0 if given, else the alphabetical highest string value will be returned.
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红色这句说的就是返回字符串。
你的第三个例子应该是有两个字符串,返回最后比较的一个。