SAS uses the SUBSTR function to extract a substring or to modify a variable's values, depending on the position of the function in the assignment statement.
When the function is 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
