跟crakman做sas base认证试题（42）

shiyiming · 发表于 2010-11-12 18:27:10

From crackman's blog on Baidu

42.The following SAS program is submitted: 
 
 data WORK.ONE; 
     Text='Australia, US, Denmark'; 
     Pos=find(Text,'US','i',5); 
 run; 
 
What value will SAS assign to Pos? 
     A. 0 
     B. 1 
     C. 2 
     D. 12
Answer: D
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本题考察的是SAS中FIND函数的应用。 
POS=FIND(Text,'US','i',5)解释为： 
从Australia, US, Denmark 字符串的第五个字符开始，忽略字符串中大小写，寻找字符串US在源字符串中的起始位置，并返回起始位置的数字给POS。 
几个问题值得思考，第一个是如果没有'i'这个参数，结果会怎么样？如果把5改成1，那么结果又如何？ 
看看SAS官网网站的解释： 
Syntax 
FIND(string,substring<,modifiers><,startpos>) 
FIND(string,substring<,startpos><,modifiers>) 
Searches for a specific substring of characters within a character string. 
Arguments
string 
specifies a character constant, variable, or expression that will be searched for substrings.
Tip: Enclose a literal string of characters in quotation marks. 
substring 
is a character constant, variable, or expression that specifies the substring of characters to search for in string.
Tip: Enclose a literal string of characters in quotation marks. 
modifiers 
is a character constant, variable, or expression that specifies one or more modifiers. The following modifiers can be in uppercase or lowercase:
i ignores character case during the search. If this modifier is not specified, FIND only searches for character substrings with the same case as the characters in substring. 
 
t trims trailing blanks from string and substring.
Note:   If you want to remove trailing blanks from only one character argument instead of both (or all) character arguments, use the TRIM function instead of the FIND function with the T modifier. 
 
Tip: If modifier is a constant, enclose it in quotation marks. Specify multiple constants in a single set of quotation marks. Modifier can also be expressed as a variable or an expression. 
startpos 
is a numeric constant, variable, or expression with an integer value that specifies the position at which the search should start and the direction of the search.
 
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