考前再请教一下70题里面的问题

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在考试前想问一下70题里自己没搞定的几道题，有劳高手啦，谢谢

--------------------------------------------------------
29.The following SAS program is sumbitted:

  data WORK.INFO;
     infile 'DATAFILE.TXT';
     input @1 Company $20. @25 State $2. @;
     if State=' ' then input @30 Year;
     else input @30 City Year;
     input NumEmployees;
  run;

How many raw data records are read during each iteration of the DATA step?

     A. 1
     B. 2
     C. 3
     D. 4

Answer: A

为什么是一个呢
-------------------------------------------------------------

35.given the SAS data set SASDATA.TWO:

  X  Y
  -- --
  5  2
  3  1
  5  6

The following SAS program is submitted:
  data SASUSER.ONE  SASUSER.TWO  OTHER;
     set SASDATA.TWO;
     if X eq 5 then output SASUSER.ONE;
     if Y lt 5 then output SASUSER.TWO;
     output;
  run;

What is the result?

     A.
data set SASUSER.ONE has 5 observations   
data set SASUSER.TWO has 5 observations
data set WORK.OTHER  has 3 observations

     B.
data set SASUSER.ONE has 2 observations   
data set SASUSER.TWO has 2 observations
data set WORK.OTHER  has 1 observations

     C.
data set SASUSER.ONE has 2 observations   
data set SASUSER.TWO has 2 observations
data set WORK.OTHER  has 5 observations

     D. No data sets are output. The DATA step fails execution due to syntax errors.

Answer: A
---------------------------------------

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

查询了下find函数还是不太懂
只知道find（string,find-string, modifiers, starting-position)
-----------------------------------------------
44.The following SAS program is submitted:

  data ONE TWO SASUSER.TWO
     set SASUSER.ONE;
  run;

Assuming that SASUSER.ONE exists, how many temporary and permanent SAS data sets are created?

     A. 2 temporary and 1 permanent SAS data sets are created
     B. 3 temporary and 2 permanent SAS data sets are created
     C. 2 temporary and 2 permanent SAS data sets are created
     D. there is an error and no new data sets are created

Answer: D
不明白为什么不是A
-----------------------------------------
35和44看上去是同一类型，看来这方面不太熟悉

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关键词：observations observation TEMPORARY following Permanent following records during

--------------------------------------------------------
29.The following SAS program is sumbitted:

  data WORK.INFO;
     infile 'DATAFILE.TXT';
     input @1 Company $20. @25 State $2. @;
     if State=' ' then input @30 Year;
     else input @30 City Year;
     input NumEmployees;
  run;

How many raw data records are read during each iteration of the DATA step?

     A. 1
     B. 2
     C. 3
     D. 4

Answer: A

为什么是一个呢

---------------------------------------------
个人认为应该是B，请高手解答。
-------------------------------------------------------------

35.given the SAS data set SASDATA.TWO:

  X  Y
  -- --
  5  2
  3  1
  5  6

The following SAS program is submitted:
  data SASUSER.ONE  SASUSER.TWO  OTHER;
     set SASDATA.TWO;
     if X eq 5 then output SASUSER.ONE;
     if Y lt 5 then output SASUSER.TWO;
     output;
  run;

What is the result?

     A.
data set SASUSER.ONE has 5 observations   
data set SASUSER.TWO has 5 observations
data set WORK.OTHER  has 3 observations

     B.
data set SASUSER.ONE has 2 observations   
data set SASUSER.TWO has 2 observations
data set WORK.OTHER  has 1 observations

     C.
data set SASUSER.ONE has 2 observations   
data set SASUSER.TWO has 2 observations
data set WORK.OTHER  has 5 observations

     D. No data sets are output. The DATA step fails execution due to syntax errors.

Answer: A
---------------------------------------------
OUTPUT; 会将该行数据输出到所有data行的三个数据集中，
if语句中的output会将满足if条件的记录输出到指定的数据集中。
---------------------------------------

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

查询了下find函数还是不太懂
只知道find（string,find-string, modifiers, starting-position)
----------------------------------------------------
modifier：i表示不区分大小写。
starting-position：这里是5，表示从第五个字母开始（即从'ralia, US, Denmark'中）找“US”；
-----------------------------------------------
44.The following SAS program is submitted:

  data ONE TWO SASUSER.TWO
     set SASUSER.ONE;
  run;

Assuming that SASUSER.ONE exists, how many temporary and permanent SAS data sets are created?

     A. 2 temporary and 1 permanent SAS data sets are created
     B. 3 temporary and 2 permanent SAS data sets are created
     C. 2 temporary and 2 permanent SAS data sets are created
     D. there is an error and no new data sets are created

Answer: D
不明白为什么不是A

--------------------------------
DATA行缺少分号。
-----------------------------------------

谢谢pobel前辈
我也觉得29应该是B，不知道其他人有什么见解

find的函数还是不太明白为什么答案是12，不知道如何得出的

data WORK.ONE;
     Text='Australia, US, Denmark';
     Pos=find(Text,'US','i',5);
  run;

这里的FIND函数是从text字符串的第五个字符开始往后找第一次出现“US”的位置（不区分大小写）。
在该字符串中，第一次出现“US”是在两个逗号之间，分别是text字符串的第12和第13个字符，因此find函数会返回12.

data WORK.ONE;
     Text='Australia, US, Denmark';
     Pos1=find(Text,'US','i',5);
     pos2=find(text,"US","i");
     pos3=find(text,"US");   
     pos4=find(text,"US ","t");
     pos5=find(text,"US ");
     pos6=find(text,"US  ","it");

     put pos1=;
     put pos2=;
     put pos3=;
     put pos4=;
     put pos5=;
     put pos6=;
  run;


pos2: 'Australia, US, Denmark'
pos3: 'Australia, US, Denmark'
pos4: 'Australia, US, Denmark'
pos5: 没有找到“US ”
pos6: 'Australia, US, Denmark'

29 题：因为每次iteration只能度一个record.
35 题：第一个if output 2 observations to sasuer.one, 第二个if ouput 2 observations to sasuser.two. 然后statement output itself 给每一个新dataset 3 observations.

     pos4=find(text,"US ","t");
     pos5=find(text,"US ");
     pos6=find(text,"US  ","it");

谢谢这个例子，能说明下这几个modifier么，没有查到，只在书上翻看到了“i”，Google出来也不清楚，多谢

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.

Tip: If the 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 that evaluates to one or more constants.

29题crackman说的是选B，我也比较困惑到底应该是1还是2

同问 请解释一下data step每次迭代读入的原始数据是指什么 以及答案到底选什么及原因