topic Re: DO loop basics in SAS Programming

DO loop basics

Sathiskumar_D — Mon, 08 May 2017 06:15:08 GMT

data WORK.LOOP;
  X = 0;
  do Index = 1 to 5  by  2;
    X = Index;
  end;
run;

Upon completion of execution, what are the values of the variables X and Index in the SAS data set named WORK.LOOP?

X = 3, Index = 5
X = 5, Index = 5
X = 5, Index = 6
X = 5, Index = 7

I knew the answer was X=5 and index=7;

Question is : When the index =5, isn't the program stop executing DO loop and gives the answer of index=5 and x=5.However, the answer was X=5 and index=.How??????

Re: DO loop basics

Kurt_Bremser — Mon, 08 May 2017 06:29:55 GMT

A do loop works like that:

1 - set the iteration variable to the start value

2 - compare to the end value

3 - if less or equal to the end value (greater or equal if the by value is negative), enter the body of the do, otherwise goto 6

4 - at the end of the body, increment by the by value

5 - goto 2

6 - end

So you see that the iteration variable needs to exceed the end value to terminate the iterative do loop.

Re: DO loop basics

ballardw — Mon, 08 May 2017 14:37:06 GMT

For added education use BY 3; and predict the values.

Re: DO loop basics

Sathiskumar_D — Mon, 08 May 2017 20:13:14 GMT

Thanks mr.KurtBremser.I am still in the learning curve.

Re: DO loop basics

kaurbal — Fri, 19 Jan 2018 04:17:47 GMT

Thanks for explaining.