sas - tilde, dlm and colon format modifier in list input

Question

There are 3 concepts i would like to clarify. :(colon format modifier), ~(tilde) and dlm=

data scores;
    infile datalines dsd;
    input name : $10. score1-score3 team ~ $25. div $;
    datalines;
Smith,12,22,46,"Green Hornets, Atlanta",AAA
FriedmanLi,23,19,25,"High Volts, Portland",AAA
Jones,09,17,54,"Vulcans, Las Vegas",AA
;
run;

Firstly, usage of : in input statement can totally replace length statement? And why i do not need : for team variable sth like team : ~ $25. ?

Secondly, why sas can automatically recoginize , is the delimiter but not " or blank ?

Answer 1

1. Colon Operator is required to tell SAS to use the informat supplied but to stop reading the value for this variable when a delimiter is encountered. Do not forget the colons because without them SAS may read past a delimiter to satisfy the width specified in the informat.

http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a000144370.htm

2. ~ Tilde is required to to treat single quotation marks, double quotation marks, and delimiters in character values in a special way. This format modifier reads delimiters within quoted character values as characters instead of as delimiters and retains the quotation marks when the value is written to a variable.

Why this is needed, because SAS has reserved certain delimiters for it's own functioning i.e. single quotation marks, double quotation marks are used to represent strings, when you want SAS to treat these quotation marks differently you have to tell explicitly it to SAS using - Tilde (~)

http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a000144370.htm

3. SAS can only automatically recognize single blank as delimiter and it cannot automatically recognize , as delimiter.You would have to explicitly tell it to SAS. In your case you have used the option dsd which does three things for you.

   • (i) It automatically by default take , as your delimiter. If you want to provide any other delimiter, you would have to specifically tell it to SAS then using dlm= option.

   • (ii) SAS treats two consecutive delimiters as a missing value and removes quotation marks from character values

   • (iii)specifies that when data values are enclosed in quotation marks, delimiters within the value are treated as character data

http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a000146932.htm