array problem

[Amy0223]

Hi community,

I'm a SAS beginner and I need help with this question below.  a) shows error "Array subscript out of range at line 77 column 14" but I'm not sure how to correct it. b and c seem to have no problems but please correct me if I'm wrong. Thank you very much!

*2. What, if anything, is wrong with the following data step program fragments?

  a);
  data c;
   array x{20};
total=0;
do i=1 to 25 by 2;
   total=sum(x(i), total);
 end;
 
 

*b);
data d;
 array x{20};
    n=0;
    do i=1 to 25 by 2;
       n=n+1;
       total=sum(x(n), total);
     end;

 *c);
 do i=0.07 to 0.08;

[Tom · Accepted solution]

For A and B the array is defined with 20 variables, but you are incrementing the index beyond 20.

B works because you are using N and not I as the index into the array and N is increasing by 1 and not 2. So it will never get larger than 20.

For A make the upper bound on the DO loop match the dimension of the Array. One way is to use the DIM() function in the DO loop.

do i=1 to dim(x) by 2;

For C you did not specify the amount to increment by so it will use 1.  So the loop will run only once since 1.07 is greater than 0.08.

A more interesting problem with trying to do something like C is that decimal fractions are not represented exactly in floating point numbers.  So it might be better to control the loop using integers (like 7 to 😎 and then divide the loop index by some factor (like 100) to make the fractional value you want to use in the loop.

[Amy0223]

Thank you so much for taking your precious time to answer my question. It's very helpful information. I really appreciate your kind help!