求教2道sas advance题目。

3644

收藏 2013-10-09

Q17：
Given the SAS data set ONE:
ONE
DIVISION SALES
A             1234
A             3654
B             5678
The following SAS program is submitted;
Data _null_;
Set one;
By division;
If first.division then
Do;
%let mfirst=sales;
end;
run;
What is the value of the macro variable MFIRST when the program finishes
execution?
A. 1234
B. sales
C. 5678
D. null
我用程序跑过，确实是B. 但为什么不是C呢，想不明白。

Q80:
The following SAS program is submitted:
%let rc=Begin;
%macro test;
data out;
set sashelp.prdsale nobs = totalobs;
if totalobs > 10 then do;
%let rc = high;
end;
else do;
%let rc = low;
end;
run;
%mend;
%let rc = Before Execution;
%test
The data set SASHELP.PRDSALE has 50 observations.
What is the value of the variable RC when the macro finishes execution?
A. low
B. high
C. Begin
D. Before Execution
答案是A，我认为是B。想不明白。

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chendonghui1987

2013-10-10 17:16:25

第一题，使用%let语句的时候就是纯文本赋值，如果想要给他变量的真实值，可以用回调函数

data a;
input division $1. sales 8.;
datalines;
A 1234
A 3654
B 5678
;
run;

Data _null_;
Set A;
By division;
If first.division then
Do;
%let mfirst=sales;
end;
run;

%put &mfirst;

Data _null_;
Set A;
By division;
If first.division then Do;
call symputx('mfirst',sales);
end;
run;

%put &mfirst;

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chendonghui1987

2013-10-10 17:30:07

第二题，应该是宏和data步处理时间的不同，具体原因记不清了，我想可能是if else语句不能限制宏命令编译期间的运行。所以最后是low

%let rc=Begin;
%macro test;
data out;
set sashelp.prdsale nobs = totalobs;
a = totalobs;
if totalobs > 10 then do;
b = 1;
%let rc = high;
end;else do;
c = 1;
%let rc = low;
end;

run;
%mend;
%let rc = Before Execution;
%test;

%put &rc.;