Execution Phase (4)

Understanding DATA Step Processing

Execution Phase

When an INPUT statement begins to read data values from a record, it uses an input pointer to keep track of its position. The input pointer starts at column 1 of the first record, unless otherwise directed. As the INPUT statement executes, the raw data in columns 1-13 are read and assigned to Item in the program data vector.

     data perm.update;
        infile invent;
        input Item $ 1-13 IDnum $ 15-19
              Instock 21-22 BackOrd 24-25;
        Total=instock+backord;
     run;

Raw Data File Invent

V---+----10---+----20---+-

Bird Feeder   LG088  3 20

6 Glass Mugs  SB082  6 12

Glass Tray    BQ049 12  6

Padded Hangrs MN256 15 20

Jewelry Box   AJ498 23  0

Red Apron     AQ072  9 12

Crystal Vase  AQ672 27  0

Picnic Basket LS930 21  0

Brass Clock   AN910  2 10

Input Pointer Control