请教一道题

A raw data file is listed below:
----|----10---|----20---|----30
10
23
20
15
The following SAS program is submitted using the raw data file as input:
data all_sales;
infile file-specification;
input receipts;
<insert statement(s) here>
run;
Which of the following completes the program and produces a running total of the values of the
RECEIPTS variable?
A. total + receipts;
B. total 0;
sum total;
C. total = total + receipts;
D. total = sum(total,receipts);

请问c和a什么区别？

Total+Receipts;<=>
Retain total 0;
Total=total+receipts
<=>
Retain total;
Sum(receipts,total);

Running total + expression 会自动initilize 并且retain total。另外一个不会，每一行total都只是missing

lsydd489 发表于 2020-10-24 05:01
Total+Receipts;
Retain total 0;
Total=total+receipts

谢谢~~~~~~~~~~