SAS Base do loop 问题

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66.The following SAS program issubmitted:

data WORK.SALES;

    do Year=1 to 5;

       do Month=1 to 12;

           X + 1;

       end;

    end;

run;

How many observations are written to theWORK.SALES data set?

    A. 0

     B. 1

    C. 5

    D. 60

The SAS System

        

Obs

         

Year

         

Month

         

X

     
      

1

      

6

      

13

      

60

想问下各位大神，为什么是6 13呢？不应该是5 12 吗？X+1 跟year month有什么关系吗？

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关键词：SAS base Base loop observations observation following written

所有语言中循环都是一样的吧

At the end of the loop, the index for year will be added 1 to be out of loop, so it will be 6. Think of " do Year=1 to 5;" as something like "year+1;do while year<=5; ". Similar scenario for month.

x+1 will be processed if it is in the loop, so it will be 60 (5 years x 12 months = 60 times) at the end.

因为循环里面无output语句，在循环过程中不向数据集输出，在循环结束时，PDV里只有一条记录，最终数据集里也只有一条记录

kunkunred 发表于 2015-2-13 06:45
At the end of the loop, the index for year will be added 1 to be out of loop, so it will be 6. Think ...

Thx! Very clear!