The _OFFSET function returns the memory offset of/within a given variable.

Syntax

offset%& = _OFFSET(variable)

Description

• The variable parameter can be any type of numerical or STRING variable name.
• API DECLARE LIBRARY parameter or TYPE names may include lp, ptr or p which designates them as a pointer type.
• _OFFSET function return values should be stored in _OFFSET type variables. As no other variable type is ‘elastic’ like _OFFSET, there can be no guarantee that any other variable type can hold the value of an _OFFSET.
• Returns the memory offset of variables, user-defined-types & elements, arrays & indices and the base offset of STRINGs.
• Offset values are currently only useful when used in conjunction with _MEM or DECLARE LIBRARY procedures.
• OFFSET values are used as a part of the _MEM variable Variable Types in QB64; variable.OFFSET returns or sets the current position in memory.
• Warning: QB64 variable length strings can move about in memory at any time. If you get the _OFFSET of a variable length sting on one line and use it on the next it may not be there anymore.** To be safe, move variable length strings into fixed length strings first.**

Example(s)

Using memcpy with the _OFFSET function values as parameters.

DECLARE CUSTOMTYPE LIBRARY
    SUB memcpy (BYVAL dest AS _OFFSET, BYVAL source AS _OFFSET, BYVAL bytes AS LONG)
END DECLARE

a$ = "1234567890"
b$ = "ABCDEFGHIJ"

memcpy _OFFSET(a$) + 5, _OFFSET(b$) + 5, 5
PRINT a$ 

12345FGHIJ

See Also

• _OFFSET (variable type)
• DECLARE LIBRARY
• DECLARE DYNAMIC LIBRARY
• Using _OFFSET