Differences between Clipper '87 and Xbase++ Foundation

Optimization of logical expressions: When compiling Clipper '87 programs Xbase++ uses the same short-cut optimization for logical expressions like Clipper 5.x:

IF <ExprA> .AND. <ExprB> 
   // <ExprB> is not executed if <ExprA> == .F. 
ENDIF 

IF <ExprA> .OR. <ExprB> 
   // <ExprB> is not executed if <ExprA> == .T. 
ENDIF 

Use the compiler switch /z to disable short-cut optimization when compiling Clipper '87 programs with Xbase++. As an alternative the short-cut optimization can be activated|deactivated for a single line of code using #pragma Shortcut(OFF|ON).

Alias names: With Clipper '87, alias names consisting only of a single letter can be specified in the USE command. With Xbase++, this is only permitted for letters above "M". For example, the following lines cannot be used with Xbase++ since they raise a runtime error:

USE Test1 ALIAS A 
USE Test2 ALIAS K 

Instead, the correct program code for Xbase++ would:

SELECT A 
USE Test1 
SELECT K 
USE Test2 

In general, it is recommended to use alias names with more than one letter.