You can use the INDEX function in SAS to return the position of the first occurrence of a string within another character string.

This function uses the following basic syntax:

INDEX(source, excerpt)

where:

• source: The string to analyze
• excerpt: The string of characters to search for within source

The following example shows how to use this function in practice.

Example: Using the INDEX Function in SAS

Suppose we have the following dataset in SAS that contains a column of names:

/*create dataset*/
data original_data;
    input name $25.;
    datalines;
Andy Lincoln Bernard
Barren Michael Smith
Chad Simpson Arnolds
Derrick Smith Henrys
Eric Millerton Smith
Frank Giovanni Goode
;
run;

/*view dataset*/
proc printdata=original_data;

We can use the INDEX function to search for the position of the first occurrence of the string “Smith” in each row:

/*find position of first occurrence of 'Smith' in name*/
data new_data;
    set original_data;
    first_smith = index(name, 'Smith');
run;

/*view results*/
proc printdata=new_data;

The new column called first_smith displays the position of the first occurrence of the string ‘Smith’ in the name column.

If ‘Smith’ is not found at all, the INDEX function simply returns a value of 0.

It’s important to note that the INDEX function is case-sensitive, so if you search for ‘smith’ instead, the INDEX function will return 0 for each string:

/*find position of first occurrence of 'smith' in name*/
data new_data;
    set original_data;
    first_smith = index(name, 'smith');
run;

/*view results*/
proc printdata=new_data;

To perform a case-insensitive search, you can use the function to first convert each string to all lowercase and then search for ‘smith’ as follows:

/*find position of first occurrence of 'smith' in name*/
data new_data;
    set original_data;
    first_smith = index(lowcase(name), 'smith');
run;

/*view results*/proc printdata=new_data;

By first converting each string to all lowercase, we’re able to use the INDEX function to perform a case-insensitive search.

The following tutorials explain how to use other common functions in SAS: