Which function in SAS is used to retrieve a substring from a character string?

The function used to retrieve a substring from a character string in SAS is SUBSTR. This function allows users to specify a starting position and a length for the substring they want to extract from a given character string.

For example, if you have a string variable and want to obtain a portion of that string, using the SUBSTR function enables you to do this efficiently. The syntax for the function is SUBSTR(string, start, length), where 'string' is the character string from which you want to extract a substring, 'start' is the position in the string where the extraction should begin, and 'length' is the number of characters to retrieve.

This function is particularly useful for data manipulation and cleaning tasks in SAS programming, as it provides a straightforward way to isolate specific sections of character data. In practice, many SAS programmers rely on the SUBSTR function when working with string information in their datasets.

In contrast, the other options listed do not represent valid SAS functions for extracting substrings. Thus, they do not fulfill the requirements of the question.