Quite often it is necessary to set a default value for a macro variable or parameter that is passed to a program. If the program is a macro, the %IF statement can be used to check if the value is provided and provide a default value if not. Since the %IF statements are not allowed outside of macros, that technique won't work for a non-macro program (e.g., a file/program that is %INCLUDEd). The following code snippet demonstrates the use of the coalescec function to assign a default value.
%global myParameter; /* ensure it exists */
%let myParameter = %sysfunc(coalescec(&myParameter,defaultValue));
If the myParameter macro variable has a value, it will be used, otherwise defaultValue will be assigned as the value. This technique can also be used in macros instead of using a %IF statement.
The coalescec function is used regardless of whether the expected value for the parameter is numeric since macro is a text manipulation facility, (i.e., everything in macro is interpreted as a character string).
Thanks to Don Henderson for sharing this tip on sasCommunity.org.
