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What is a function in SAS

• A function is a component of the SAS language that accepts input, performs an operation, and returns a value
• Functions can be used in DATA steps, WHERE expressions, PROC SQL, and many other places where SAS expects an expression

What is a character function

• A character function works with text values and returns information derived from character strings or modified character strings

Character functions that change case

Function	Definition
UPCASE	Converts letters in a character string to uppercase.
LOWCASE	Converts letters in a character string to lowercase.
PROPCASE	Converts text to proper case by capitalising the first letter of each word and lowercasing the remaining letters.

Create sample data

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; Copy Code View Log

Create upper, lower, and proper case versions of the string variable

• The original variable remains unchanged because the function results are written to new variables
• Compare the results row by row and observe how each function transforms the same source string differently

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

• Notice that `propcase` depends on the word separators SAS recognises by default
• For example, `Con)med` behaves differently from `Con(med` because the separators are not identical

View Data

Character functions that return string length

Function	Definition
LENGTH	Returns the number of characters excluding trailing blanks and returns 1 for a blank string.
LENGTHN	Returns the number of characters excluding trailing blanks and returns 0 for a blank string.

Create sample data

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

Compare LENGTH and LENGTHN

• The two functions usually return the same value except when the string is blank
• This difference is important when checking whether a character value is truly empty

data lengths02; set lengths01; len1=length(string); len2=lengthn(string); run; Copy Code View Log

• Inspect the blank row carefully and compare `len1` with `len2`

View Data

Use SCAN to extract words from a string

Function	Definition
SCAN	Extracts a word from a string based on word position and delimiters.

Create sample data

data scan_example; infile datalines truncover; input string $50.; obs=_n_; datalines; Hello World SAS!Programming$Language Data-Analysis in Healthcare Open(Source)Tools ; run; Copy Code View Log

Extract words using SCAN

• The second argument of `scan` specifies which word to return
• The optional third argument can be used to define custom delimiters

data scan_result; set scan_example; first_word = scan(string,1); second_word = scan(string,2); third_word = scan(string,3); custom_word = scan(string,2,'()'); run; Copy Code View Log

• Review the output and compare the default delimiter behaviour with the custom delimiter example

View Data

Use SUBSTR to extract or modify part of a string

Function	Definition
SUBSTR	Extracts part of a string and can also be used on the left side of an assignment to replace part of a string.

Create sample data

data substr_example; infile datalines truncover; input string $50.; datalines; Hello World SAS Programming Data Science and Analytics 1234567890 ; run; Copy Code View Log

Extract and modify parts of a string using SUBSTR

• When used on the right side of an assignment, `substr` extracts characters
• When used on the left side of an assignment, `substr` can replace characters in the target string

data substr_result; set substr_example; first_5_chars = substr(string,1,5); from_7_to_end = substr(string,7); modified_string = string; substr(modified_string,7,5) = '#####'; run; Copy Code View Log View Data

Use FIND to locate a substring

Function	Definition
FIND	Returns the position of the first occurrence of a substring within a string.

Create sample data

data find_example; infile datalines truncover; input string $60.; datalines; Adverse Event Started Concomitant Medication Screen Failure Treatment Emergent Adverse Event ; run; Copy Code View Log

Use FIND to locate text in a string

• `find` returns the starting position of the searched text
• If the text is not found, the function returns 0
• The optional modifiers can be used for case-insensitive searching

data find_result; set find_example; pos_event = find(string,'Event'); pos_event_i = find(string,'event','i'); run; Copy Code View Log View Data

Key points to remember

• Character functions are essential for cleaning, parsing, and standardising text in SAS
• `upcase`, `lowcase`, and `propcase` help standardise case
• `length` and `lengthn` help measure string content, but behave differently for blank strings
• `scan` extracts words, and `substr` extracts or replaces character ranges
• `find` identifies the position of a substring inside a string