Transforming Data with SAS Functions
Modifying Character Values with Functions

 

There is a second use for the SUBSTR function. This function can also be used to replace the contents of a character variable. For example, suppose the local phone exchange 622 was replaced by the exchange 433. You need to update the character variable Phone in Hrd.Temp to reflect this change.

SAS Data Set Hrd.Temp

City	State	Zip	Phone	BeginDate	EndDate	PayRate	Days	Hours
CARY	NC	27513	6224549	14567	14621	10	11	88
CARY	NC	27513	6223251	14524	14565	8	25	200
CHAPEL HILL	NC	27514	9974749	14570	14608	40	26	208
RALEIGH	NC	27612	6970450	14516	14527	15	10	80

You can complete this modification by using the SUBSTR function. The syntax of the SUBSTR function, when used to replace a variable's values, is identical to the syntax for extracting a substring. SUBSTR(argument,position<,n>) However, in this case, the first argument specifies the character variable whose values are to be modified. the second argument specifies the position at which the replacement is to begin. the third argument specifies the number of characters to replace. If n is omitted, the remainder of the value is replaced. Positioning the SUBSTR Function SAS software uses the SUBSTR function to extract a substring or modify a variable's values based on the position of the function in the assignment statement. When the function appears on the right side of an assignment statement, the function returns the requested string. MiddleInitial=substr(middlename,1,1); But if you place the SUBSTR function on the left side of an assignment statement, the function is used to modify variable values. substr(region,1,3)='NNW'; When the SUBSTR function modifies variable values, the right side of the assignment statement must specify the value to place into the variable. For example, to replace the fourth and fifth characters of a variable named Test with the value 92, you write the following assignment statement: substr(test,4,2)='92'; Test Test S7381K2 S7392K2 S7381K7 S7392K7