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Function definition

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A function is a component of the SAS programming language that can accept input, perform a computation or other operation, and return a value

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Where can a SAS function can be used?

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in data step programming
in a WHERE expression (where statement or where clause)
in proc sql

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What is a character function?

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A SAS function that returns information based on character data is called a character function

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Character functions that converts the case of characters

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Function	Defintion
UPCASE	Upcase function is used for converting english alphabet letters of a variable's value to uppercase
LOWCASE	Lowcase function is used for convering englight alphabet letters of a variable's value to lowercase
PROPCASE	Propcase function is used for converting all words of a variable's value to proper case. That is, propcase function converts the first letter of each 'word' to uppercase (and other letters of the word to lowercase). By default these characters are considered word separators: blank, forward slash, hyphen, open parenthesis, period

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Create sample data

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data case01;
     infile datalines truncover;
     input string $50.;
     obs=_n_;
  datalines;
  www.google.com
  your name is Alfred
  His Name is John
  TREATMENT 1
  aDverSE event
  Con(med
  Con)med
  ;
  run;

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Create 3 new variables named upper, lower and proper by appying upcase, lowcase and propcase functions respectively on sring variable

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As the returned values from the functions are assigned to new variables here, the original variable values remain unaltered
Notice that in the newly created upper variable, on all observations all the alphabets have been converted to uppercase
Notice that in the newly created lower variable, on all observations all the alphabets have been converted to lowercase
Notice that in the newly created proper variable, on observations where each word is separated by a space,period,open parenthesis, the first letter of the word is converted to uppercase and other letters of the word are converted to lowercase. On observation 7, the first letter of text 'med' is not converted to uppercase because a closing parenthesis is not considered as a word separator and hence entire text 'con)med' is considered as single word

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data case02;
     set case01;
     upper=upcase(string);
     lower=lowcase(string);
     proper=propcase(string);
  run;

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Character Functions that return the length of the strings

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Function	Definition
LENGTH	Length function is used for obtaining the number of characters in a character string excluding trailing blanks, retruns a value of 1 for a blank value
LENGTHN	LengthN function is used for obtaining the number of characters in a character string excluding trailing blanks, retruns 0 for blank value

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Create sample data

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data lengths01;
     infile datalines truncover;
     input string $50.;
  datalines;
  google
  google.com
  google  .com
   
  www.google.com
  g
  ;
  run;

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Create two new variables length and lengthn by obtaining the length of string variable using LENGTH and LENGTHN functions

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Notice in the output that both length and lengthn returns the same value on all observations except 4th observation where string variable has a null value. As described in definition, Length function returns 1 for null string and LengthN function returns 0 null string
So, caution should be exercised when LENGTH function is used to identify a null string as it returns a value of 1 when there is one character in the value or the string is null.

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data lengths02;
     set lengths01;
     length=length(string);
     lengthn=lengthn(string);
  run;