The BEGIN (UN)CHECKED and END (UN)CHECKED keywords mark a block of statements that are compiled with overflow checking enabled or disabled
BEGIN CHECKED
statements
END CHECKED
BEGIN UNCHECKED
statements
END CHECKED
statements | One or more statements or expressions that are compiled with the specified overflow checking |
BEGIN CHECKED ... END CHECKED ensures that a block of code is compiled with a clear overflow checking option, regardless of the compiler option -ovf.
BEGIN CHECKED
LOCAL intValue as INT
LOCAL dwordValue as DWORD
intValue := -1
dwordValue := (DWORD) intValue // Overflow error
END CHECKED
BEGIN UNCHECKED
LOCAL intValue as INT
LOCAL dwordValue as DWORD
intValue := -1
dwordValue := (DWORD) intValue // NO Overflow error, dwordValue now has the value UInt32.MaxValue
END UNCHECKED