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On 05/03/2006, at 8:19 PM, Mike Pantzopoulos - (H/O) wrote:
I understood from the manual that the system converts the parameter passed from the calling RPG into a temporary vatiable length field if the prototype is declared as *varsize. In the calling RPG, the parameter can be declared as any length up to the prototype declaration. It's declared as a noraml variable, and If that's the case, then why can't they convert the CL variable in the same fashion and avoid this low-level explicitness?
Because the type conversion is performed by the RPG IV compiler. It uses the prototype definition to determine the appropriate target parameter type. This is done at the time of the compile. It is not a run-time function.
CL has no access to the function prototype and there is no easy way, even for the OS, to determine the type and attributes of a parameter thus because CL does not know anything about the function interface it cannot convert the parameters from one type to another.
In your case, you were passing a fixed-length variable (20 bytes) into a function that expected a varying length variable (22-bytes). Thus the function was interpreting the first two bytes of data as the varying length. For many data values this would result in a number larger than the maximum of 20 bytes the variable is capable of holding hence the exception.
Note also that you say *VARSIZE above but the variable that was causing the problem was *VARYING. These are not the same thing. *VARSIZE will work as expected between CL and RPG IV because CL passes the operational descriptor for character variables which includes the length of the passed data. As long as the receiving procedure correctly retrieves the operational descriptor and limits its operations on the variable to the length specified in the operation descriptor everything will work as expected.
CL has no direct support for *VARYING character strings so these must be built by the programmer using the method I described previously.
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