Hi, %let y = abc; x = &y; here x will get the value abc ie x = abc. So SAS assumes that abc is a variable in itself however when you do. x = "&y" x = "abc" hence SAS compiler comes to know its a character value. For numeric values SAS performs the calculations implicitly. %let y =5; x = y is going to give you x = 5 and here 5 is a numeric value hence its not considered as a variable. I hope this helps. PS : I did not go through the whole thread so I might be answering something totally different from what you were asking. CHEERS

On 8/17/05, Ching Fang Chi <chingfang@gmail.com> wrote: > > I was reading document about macro variable. > So I tried the following code. > ================================= > %let name = derek; > > data try1; > people1 = &name; > %put &name; > put people1=; > > %let name = karen; > > people2 = &name; > %put &name; > put people2=; > run; > > proc print data=try1; > run; > ================================= > In the log the value of name were shown correctly: derek and karen. > But in the output window, the result was: > Obs people1 derek people2 karen > 1 . . . . > > I guess the macro variable reference resolvation was wrong. > So I gave a second try. > ================================= > %let name = derek; > > data try2; > people1 = "&name"; /*add quotation mark here*/ > %put &name; > put people1=; > > %let name = karen; > > people2 = "&name"; /*add quotation mark here*/ > %put &name; > put people2=; > run; > > proc print data=try2; > run; > ================================= > I added quotation marks in the assignment statements for variable people1 > and people2. When I checked the output result, it showed: > Obs people1 people2 > 1 derek karen > > It seemed that after I added the quatation marks the value defined by %let > statement could be resolved correctly. > > Then I gave a third try. > ================================= > %let name = 5; /*change the value from derek to 5 */ > > data try3; > people1 = "&name"; /*still keep the quotation mark*/ > %put &name; > put people1=; > > %let name = 10; > > people2 = "&name"; /*still keep the quotation mark */ > %put &name; > put people2=; > > run; > > proc print data=try3; > run; > ================================= > I changed the value of macro variavle name from derek to 5. > The result was similar to the second one: > Obs people1 people2 > 1 5 10 > > which also seemed right for me. I decided to take off the quotation > marks like the one I did in the first try. > ================================= > %let name = 5; > > data try4; > people1 = &name; /*take off the quotation mark*/ > %put &name; > put people1=; > > %let name = 10; > > people2 = &name; /*take off the quotation mark*/ > %put &name; > put people2=; > > run; > > proc print data=try4; > run; > ================================= > To my surprise the result was the same as the third try. > Obs people1 people2 > 1 5 10 > > I was very confused about the result since quotation mark was not > needed. Then I went on another try: > ================================= > %let name = derek; /*change back the value from 5 to derek */ > > data try5; > people1 = &name; > %put &name; > put people1=; > > %let name = 10; > > people2 = &name; > %put &name; > put people2=; > > run; > > proc print data=try5; > run; > ================================= > The result was: > Obs people1 derek people2 > 1 . . 10 > > The result was good for variable peopl2. > If I added back the quotation mark to the assignment statement > for people1, the result would be: > ================================= > %let name = derek; > > data try6; > people1 = "&name"; /*add back the quotation mark */ > %put &name; > put people1=; > > %let name = 10; > > people2 = &name; > %put &name; > put people2=; > > run; > > proc print data=try6; > run; > ================================= > Obs people1 people2 > 1 derek 10 > > I don't know if the weird result came from the incorrect usuage of > macro variable reference in an assignment statement(like people1 = &name). > Does quotation mark really matter? or I misunderstood about macro variable > reference? It seemed like if I assign a string value, I would have to use > quotation mark; If I assign a numeric value then quotation mark is not > necessary. > > But I also read that the value assigned to a macro variable is treated as > character string. So I can't figure out how macro reference is resolved > actually. Can anyone help me solving the problem? > > Thanks again for any comments. > > Cheers, > Ching Fang >

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