= SAS Macro Functions =

<<TableOfContents>>

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== 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.)));
}}}

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== 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'           ||



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CategoryRicottone