Mistakes in Data

Sometimes there are mistakes in the data. If a group of characters is read that can not be converted into a number, QBasic assigns a 0 to the variable. Here is a file (say that it is called ERRR.DAT) that is supposed to be a file of integers.

12.5
error
10.9

The second line does not contain a proper number. Say that this program was run with this file:

OPEN "ERRR.DAT" FOR INPUT AS #1  ' Open the file for INPUT
INPUT #1, NUM                    ' Read in the first number
PRINT NUM                        ' Print out the first number
INPUT #1, NUM                    ' Read in the second number
PRINT NUM                        ' Print out the second number
INPUT #1, NUM                    ' Read in the third number
PRINT NUM                        ' Print out the third number
END

When this program is run, it prints out:

12.5
0
10.9

It can be difficult to catch an error like this.