CVA_START
Macro to initialize variadic argument list object variable
Syntax:
cva_start( argument_list, last_param )
Parameters:
Description:
In a variadic procedure definition, argument_list is a variable having the cva_list type and must be initialized with cva_start to work with the variable length argument list passed to the procedure.
last_param is the last parameter before the ellipsis ... in the variadic procedure definition.
cva_start can only be used in variadic procedures. A variadic procedure is declared or defined by specifying the ellipsis ... as the last parameter, and will accept a variable number of arguments when calling the procedure.
cva_start is like a constructor for the variadic argument_list object and must eventually have a matching call to cva_end, which is like a destructor. After cva_end for argument_list has been called, argument_list can be reused and reinitialized with another call to cva_start. The cva_start and cva_end calls must both be called in pairs in the same procedure (for cross platform compatibility).
cva_copy is similar to cva_start except it initializes a variadic argument_list object from an already initialized variadic argument_list object, like a copy constructor.
last_param is the last parameter before the ellipsis ... in the variadic procedure definition.
cva_start can only be used in variadic procedures. A variadic procedure is declared or defined by specifying the ellipsis ... as the last parameter, and will accept a variable number of arguments when calling the procedure.
cva_start is like a constructor for the variadic argument_list object and must eventually have a matching call to cva_end, which is like a destructor. After cva_end for argument_list has been called, argument_list can be reused and reinitialized with another call to cva_start. The cva_start and cva_end calls must both be called in pairs in the same procedure (for cross platform compatibility).
cva_copy is similar to cva_start except it initializes a variadic argument_list object from an already initialized variadic argument_list object, like a copy constructor.
Examples:
'' typical usage of iterating through all arguments
Sub proc CDecl(count As Integer, ... )
Dim args As cva_list
cva_start( args, count )
For i As Integer = 1 To count
Print cva_arg( args, Integer )
Next
cva_end( args )
End Sub
proc( 4, 4000, 300, 20, 1 )
Sub proc CDecl(count As Integer, ... )
Dim args As cva_list
cva_start( args, count )
For i As Integer = 1 To count
Print cva_arg( args, Integer )
Next
cva_end( args )
End Sub
proc( 4, 4000, 300, 20, 1 )
'' example of using cva_start to get the first argument
'' then restarting to get all the arguments
Sub proc CDecl(count As Integer, ... )
Dim args As cva_list
'' get the first argument only
cva_start( args, count )
Print cva_arg( args, Integer )
cva_end( args )
'' restart and get all the arguments
cva_start( args, count )
For i As Integer = 1 To count
Print cva_arg( args, Integer )
Next
cva_end( args )
End Sub
proc( 4, 4000, 300, 20, 1 )
'' then restarting to get all the arguments
Sub proc CDecl(count As Integer, ... )
Dim args As cva_list
'' get the first argument only
cva_start( args, count )
Print cva_arg( args, Integer )
cva_end( args )
'' restart and get all the arguments
cva_start( args, count )
For i As Integer = 1 To count
Print cva_arg( args, Integer )
Next
cva_end( args )
End Sub
proc( 4, 4000, 300, 20, 1 )
Version:
- Since fbc 1.07.0
Dialect Differences:
- Not available in the -lang qb dialect unless referenced with the alias __cva_start.
Differences from QB:
- New to FreeBASIC
See also:
Back to Procedures
Back to Variable Argument list
