find(str,substr[,modifiers][,start_pos])
find(str,substr[,start_pos][,modifiers])
Searches a string for a substring and returns the first position
at which it’s found, or zero (0) if it’s not found. For a descrip-
tion of  start_pos see any<chartype> (p. 10). modifiers is one
or more of the values listed in the following table.
modifiers Means
i Ignore character case during the search. If this modifier
is omitted, the search is case-sensitive.
t Trim trailing spacing from str and substr.
Examples:
str='She sells seashells? Yes, she does.';
find(str,'she ') → 27.
find(str,'she ','i') → 1.
find(str,'she ','i',5) → 27.
find(str,'she ','it',5) → 14.
find(str,'she ','it') → 1.

版主说得挺清楚了，楼主sas help多看看，很有"帮助"的

谢谢各位~本人不才~
help里没看懂~才来请教的~
~~o(>_<)o ~~

find有两种返回值，找到的返回找到的第一个字符位置，没找到则返回“0”，一般结合字符截取函数如substr（）使用

str='She sells seashells? Yes, she does.';
find(str,'she ') → 27.   
      区分大小写，从str第1个字符开始查找，返回位置27
find(str,'she ','i') → 1.
     不区分大小写，从str第1个字符开始查找，返回位置1
find(str,'she ','i',5) → 27.
     不区分大小写，从str第5个字符开始查找，返回位置27
find(str,'she ','it',5) → 14.
      不区分大小写，不匹配‘she ’和str空白字符，从str第5个字符开始查找，返回位置14
find(str,'she ','it') → 1.
       不区分大小写，不匹配‘she ’和str空白字符，从str第1个字符开始查找，返回位置1

楼主这样你该明白了吧