Scripting Guide - SAS

Chapter 8 Programming Methods 215
Advanced Programming Concepts
Throwing and Catching Exceptions
A script can stop itself by executing the Throw( ) function. If you want to escape from part of a script
when it is in an error condition, you can enclose it in a Try( ) expression.
Try takes two expression arguments. It starts by evaluating the first expression, and if or when the first
expression throws an expression by evaluating Throw, it does the following:
1. Immediately stops evaluating that first expression.
2. Returns nothing
3. Evaluates the second expression.
Throw does not require an argument but has two types of optional arguments. If you include a
character-valued expression as an argument, throwing stores that string in a global named exception_msg;
this is illustrated in the first example below.
Examples
For example, you can use Try and Throw to escape from deep inside For loops.
a = [1 2 3 , 4 5 . , 7 8 9];
b = a;
nr = nrow(a);
nc = ncol(a);
//a[2,3]=2; //uncomment this line to see the "Missing b" outcome
try(
sum = 0;
for(i=1,i