Structures let you call an external routine that expects a structure argument containing a field whose value is a pointer to another structure. You can use the copy action statement with the handle of built-in function to copy the handle of the quoted name of one structure into an integer field in another structure or to an ESL integer variable. For example:

 

structure Employee is 

string  Name 

integer AddressPtr

end structure

 

structure Address is 

string Street

                City

                State

                Zip 

end structure

 

# Structure variable declarations:

structure Employee Emp structure Address Addr

 

# External subroutine declaration:

subroutine PRINT_ADDRLABEL ( structure Employee: EmpRec )

library "Prt_Rtns"

 

copy ScreenStreet to Addr.Street 

copy ScreenCity         to Addr.City

copy ScreenState         to Addr.State 

copy ScreenZip         to Addr.Zip

copy ScreenName         to Emp.Name

 

# Copy handle of one structure into field in another 

copy handle of "Addr" to Emp.AddressPtr

 

# Call routine to print address label 

call PRINT_ADDRLABEL (Emp)

 

This example defines two structure types, Employee and Address. Employee contains an integer field, AddressPtr, designed to hold a pointer. The example declares two structure variables, Emp and Addr, and a subroutine, PRINT_ADDRLABEL. It populates the two structure variables with data, and copies the handle of the quoted name of the Addr structure variable into the Emp structure variable. Finally, it calls the subroutine PRINT_ADDRLABEL, passing the Emp structure variable as an argument.