Release 10.1A: OpenEdge Development:
Programming Interfaces

Avoiding common HLC errors

To ensure compatibility between your HLC functions and Progress, consider the following when writing your functions:

An HLC library function does not always return character and decimal data as null-terminated strings. For example, the pvar parameter of the prordc() function contains character data without null termination. To terminate such a string with the null character, you must add it yourself.
When you check the value of a field or variable that HLC returns, check for the Unknown value (?). The field might not always contain a valid value.
If you return from your top-level function without setting an appropriate return code value, Progress might raise an error condition unexpectedly. See the "Returning error codes from a top-level function" section section for more information.
Use the promsgd() HLC library function to display messages directly to the terminal. Using the standard C function printf() might produce unexpected results when used to send raw data to a terminal.