Given the following data step:
data WORK.GEO;
infile datalines;
input City $20.;
if City=’Tulsa’ then
State=’OK’;
Region=’Central’;
if City=’Los Angeles’ then
State=’CA’;
Region=’Western’;
datalines;
Tulsa
Los Angeles
Bangor
;
run;
After data step execution, what will data set WORK.GEO contain?
A.
| Obs | City | State | Region |
| 1 | Tulsa | OK | Western |
| 2 | Los Angeles | CA | Western |
| 3 | Bangor | Western |
B.
| Obs | City | State | Region |
| 1 | Tulsa | OK | Western |
| 2 | Los Angeles | CA | Western |
| 3 | Bangor |
C.
| Obs | City | State | Region |
| 1 | Tulsa | OK | Central |
| 2 | Los Angeles | CA | Western |
| 3 | Bangor | Western |
D.
| Obs | City | State | Region |
| 1 | Tulsa | OK | Central |
| 2 | Los Angeles | CA | Western |
| 3 | Bangor |
Answer: A
注解：程序对Region进行了2次赋值操作，第一次赋值为Central，第二次赋值操作覆盖了第一次的值，把Region改为了Western。另外需要注意的是，题目中的IF/THEN语句，在完成对State的复制后就结束了，对Region的赋值语句并不受IF/THEN的影响。如需输出D中的结果，程序应改为：
data WORK.GEO;
infile datalines;
input City $20.;
if City=’Tulsa’ then do;
State=’OK’;
Region=’Central’;
end;
if City=’Los Angeles’ then do;
State=’CA’;
Region=’Western’;
end;
datalines;
Tulsa
Los Angeles
Bangor
;
run;
Really appreciate your answers. But I am finding it hard to understand the explanation of all answers as the language is not just english. Any solution for that?