SAS Macro Functions
Contents
Defining Functions
A macro function resolves to a value. To be as flexible as a macro function, certain restrictions must be adhered to. Chiefly a data step or process cannot be invoked.
%macro exist(dsname); %sysfunc(exist(&dsname)) %mend exist;
Using SAS Functions
To use a SAS function inside a macro, the %sysfunc macro function must be used. %sysfunc cannot take nested SAS functions, but can take nested macro functions.
%let mon_title = %sysfunc(left(%qsysfunc(mdy(&mon,1,&curr_yr), monname9.)));
Remember the availability of the quoted %qsysfunc. In this context, the most contentious special character is the comma, which can be confused for an argument delimiter.
This results in an error:
%let date=%sysfunc(left(%sysfunc(today(),worddate.)));
/* ^
June 7, 2002
^
left(June 7, 2002)
^
Error: `left` takes only one argument
*/This will not:
%let date=%sysfunc(left(%qsysfunc(today(),worddate.)));
Using Functions in the Data Step
A macro function can be called within a data step using resolve(). resolve actually can be used to get the value of any type of macro, including a macro variable.
resolve() can be called in three ways:
method1 = resolve("&mymacro");
method2call = '&mymacro';
method2 = resolve(method2call);
method3 = resolve(cats('&','my','macro'));
Built-in Functions
Given:
%let a=Foo; %let b=%nrstr(&a bar); %let c=%nrstr(&a);
The following functions can be used as:
Name |
Action |
Example Input |
Example Result |
%sysfunc(function call) |
Evaluates a function call |
|
|
%qsysfunc(function call) |
Same, but masks value |
|
|
%substr(value,position,length) |
Copies a substring from a value by literal position |
%substr(&c,1,2) |
'Foo' |
%qsubstr(value,position,length) |
Same, but masks value |
%qsubstr(&c,1,2) |
'&a' |
%scan(value,index,delimiter) |
Copies a substring from a value by parsed position |
%scan(&c,1,' ') |
'Foo' |
%qscan(value,index,delimiter) |
Same, but masks value |
%qscan(&c,1,' ') |
'&a' |
%upcase(value) |
Translates lowercase into uppercase |
%upcase(&c) |
'Foo' |
%qupcase(value) |
Same, but masks value |
%qupcase(&c) |
'&A' |
%lowcase(value) position |
Translates uppercase into lowercase |
%lowcase(&c) |
'Foo' |
%qlowcase(value) |
Same, but masks value |
%qlowcase(&c) |
'&a' |
%cmpres(value) |
Strips leading/trailing and multiple whitespace |
|
|
%qcmpres(value) |
Same, but masks value |
|
|
%left(value) |
Strips leading whitespace |
|
|
%qleft(value) |
Same, but masks value |
|
|
%eval(expression) |
Evaluates expression using integer arithmetic |
%eval(10/3) |
'3' |
%sysevalf(expression) |
Evaluates expression using floating point arithmetic |
%sysevalf(10/3) |
'3.333333' |