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Session 7, Chapter 6 From SAS 9.3 Macro Language Reference Macro Expressions P 71.

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Presentation on theme: "Session 7, Chapter 6 From SAS 9.3 Macro Language Reference Macro Expressions P 71."— Presentation transcript:

1 Session 7, Chapter 6 From SAS 9.3 Macro Language Reference Macro Expressions P 71

2 &Eval - p %let A=2; %let B=5; %let operator=+; %put The result of &A &operator &B is %eval(&A &operator &B).; The result of is 7.

3 Macro Language Operators – p 73 Table 6.3 P 73 ** + - -^~ etc

4 The macro facility is a string handling facility – p * Use %EVAL in a %LET statement; %let a=%eval(1+2); %let b=%eval(10*3); %let c=%eval(4/2); %let i=%eval(5/3); %put The value of a is &a; %put The value of b is &b; %put The value of c is &c; %put The value of I is &i; ******** Note answers are all integer;

5 %SYSEVAL p. 75 * USE SYSEVAL INSTEAD; %let a=%sysevalf(10.0*3.0); %let b=%sysevalf( ); %let c=%sysevalf(5/3); %put 10.0*3.0 = &a; %put = &b; %put 5/3 = &c; * Note answers can be floating point now. ;

6 How Macro Evaluates Logical Expression p 76 %macro compnum(first,second); %if &first>&second %then %put &first is greater than &second; %else %if &first=&second %then %put &first equals &second; %else %put &first is less than &second; %mend compnum; *Invoke the COMPNUM macro with these values; %compnum(1,2) %compnum(-1,0) ; The following results are displayed in the log: 1 is less than 2 -1 is less than 0

7 Other comparisons Floating point p – Type in the code on top of 77 & test Compare character operands in logical expressions p 77 – Type in example code middle of p 77 & test

8 Chapter 7 – Macro Quoting – p 79 Why doesn’t this work? P 81 %let print=proc print; run;; Why does this work? %let print=%str(proc print; run;); What does %str() do?

9 NRSTR%() - P 88 Use NRSTR%() when there is a macro variable name in the expression that you don’t want evaluated – this prevents the macro variable from being evaluated %macro example; %local myvar; %let myvar=abc; %put %nrstr(The string &myvar appears in log output,); %put instead of the variable value.; %mend example; %example The string &myvar appears in log output, instead of the variable value.

10 Example 2 %NRSTR Type in example middle of p 88 %macro credits(d=%nrstr(Mary&Stacy&Joan Ltd.)); footnote "Designed by &d"; %mend credits; Run with %credits() Observe output. What happens if you use %SRT instead? Try it.

11 BQuote p 89 Use BQUOTE() when an expression has unmatching quotes such as Jones’s NRBQUOTE() when there is a macro expression you don’t want evaluated + unmatching quotes.

12 Example BQUOTE – p 90 ** Example BQWUOTE p 90; data test; store="Susan's Office Supplies"; call symput('s',store); run; %macro readit; %if %bquote(&s) ne %then %put *** valid ***; %else %put *** null value ***; %mend readit; %readit ; * Observe output in log – what if you don’t use BQUOTE?;

13 SuperQ – p 92 ***********EXAMPLE SUPERQ ********AND %WINDOW; * It masks items that might require macro quoting; %window ask 'Enter two values:' val 15 attr=underline; %macro a; %put *** This is a. ***; %mend a; %macro test; %display ask; %put *** %superq(val) ***; /* Note absence of ampersand */ %mend test; *invoke the macro TEST; %test

14 Ch 9, 10 & 11 Ch 9 - Storing and Reusing Macros – read on your own Ch 10 – Macro Errors – Note bullets on p 121 – See Note bottom p 129 double and single quotes Ch 11 – Writing Efficient Code - read on your own

15 Ch 12 – Macro Language Elements Review Table 12.1 p 156 Table 12.2 p 157 Table 12.3 p 158 Table 12.4 p 159 Table 12.5 p 160 Table 12.9 p 166

16 End


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