"Illegal Function Call" Using Asc with Uninitialized String (80411)

MORE INFORMATION

This information is documented in the QB.EXE 4.5 or QBX.EXE 7.0/7.1 online Help for the Asc function, but is not available when the error message is received when the Help option is chosen. Below are two code examples that reproduce the error. By assigning the string to any value, the Asc function works without error.

The following code examples will fail:

Code Error Example 1

PRINT ASC(x$)
				

Code Error Example 2

x$ = ""
PRINT ASC(x$)
				

The following code examples will work correctly:

Correct Code Example 1

x$=" "
PRINT ASC(x$)
				

Output: 32

Correct Code Example 2

x$="Pearl Jam"
PRINT ASC(x$)
				

Output: 80

To work around the error, check the length of the string with the Len function in an IF...THEN statement to ensure it is greater than zero before passing the string as an argument to the Asc function. The following code example demonstrates the workaround. The code allows you to only use the Asc function when something has been assigned to the string, otherwise it sets the Asc value to zero. Assigning Temp$ to CHR$(0) returns a 0, but assigning it "" gives you an "Illegal function call".

If LEN(Temp$) > 0 THEN
    ' Use the Asc Function
    AscVal = ASC(Temp$)
Else
    AscVal = 0
End if
PRINT AscVal