Operator @ (Address of)
Returns the address of a string literal, variable, object or procedure
Syntax:
Usage:
result = @ rhs
Parameters:
rhs
The string literal, variable, object or procedure to retrieve the address of.
TReturn Value:
Returns the address of the right-hand side (rhs) operand.
Description:
Operator @ (Address of) returns the memory address of its operand.
When the operand is of type String, the address of the internal string descriptor is returned. Use Operator Strptr (String pointer) to retrieve the address of the string data.
The operand cannot be an array, but may be an array element. For example, "@myarray(0)" returns the address of "myarray(0)".
This operator can be overloaded for user-defined types as a member Operator using the appropriate syntax.
When the operand is of type String, the address of the internal string descriptor is returned. Use Operator Strptr (String pointer) to retrieve the address of the string data.
The operand cannot be an array, but may be an array element. For example, "@myarray(0)" returns the address of "myarray(0)".
This operator can be overloaded for user-defined types as a member Operator using the appropriate syntax.
Examples:
'This program demonstrates the use of the @ operator.
Dim a As Integer
Dim b As Integer
Dim addr As Integer Ptr
a = 5 'Here we place the values 5 and 10 into a and b, respectively.
b = 10
'Here, we print the value of the variables, then where in memory they are stored.
Print "The value in A is ";a;" but the pointer to a is ";@a
Print "The value in B is ";b;" but the pointer to b is ";@b
'Now, we will take the integer ptr above, and use @ to place a value into it.
'Note that the * will check the value in the ptr, just as @ checked the ptr
'for a normal variable.
addr = @a
Print "The pointer addr is now pointing at the memory address to a, value: ";*addr
addr = @b
Print "The pointer addr is now pointing at the memory address to b, value: ";*addr
Dim a As Integer
Dim b As Integer
Dim addr As Integer Ptr
a = 5 'Here we place the values 5 and 10 into a and b, respectively.
b = 10
'Here, we print the value of the variables, then where in memory they are stored.
Print "The value in A is ";a;" but the pointer to a is ";@a
Print "The value in B is ";b;" but the pointer to b is ";@b
'Now, we will take the integer ptr above, and use @ to place a value into it.
'Note that the * will check the value in the ptr, just as @ checked the ptr
'for a normal variable.
addr = @a
Print "The pointer addr is now pointing at the memory address to a, value: ";*addr
addr = @b
Print "The pointer addr is now pointing at the memory address to b, value: ";*addr
'This program demonstrates how the @ symbol can be used
'to create pointers to subroutines.
Declare Sub mySubroutine ()
Dim say_Hello As Sub()
say_Hello = @mySubroutine 'We tell say_Hello to point to mySubroutine.
'The sub() datatype acts as a pointer here.
say_Hello() 'Now we can run say_Hello just like mySubroutine.
Sub mySubroutine
Print "hi"
End Sub
'to create pointers to subroutines.
Declare Sub mySubroutine ()
Dim say_Hello As Sub()
say_Hello = @mySubroutine 'We tell say_Hello to point to mySubroutine.
'The sub() datatype acts as a pointer here.
say_Hello() 'Now we can run say_Hello just like mySubroutine.
Sub mySubroutine
Print "hi"
End Sub
Dialect Differences:
- In the -lang qb dialect, this operator cannot be overloaded.
Differences from QB:
- New to FreeBASIC
See also:
Back to Pointer Operators
Back to Operators
