ctypes: how to make a structure pointer to point to a buffer

[人言落日是天涯，望极天涯不见家]

first, I'm try the POINTER to convesion the pointer type. but failed.

class STUDENT(Structure):
_fields_ = [('name',  c_int),
('id',   c_int),
('addition',c_ubyte)]

buffer = c_byte * 1024
student_p = cast(buffer, POINTER(STUDENT))

The parameter of the POINTER must be ctypes type.
How could I attach the buffer pointer to the structure STUDENT ?

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Re: ctypes: how to make a structure pointer to point to a buffer

[Diez B. Roggisch]

人言落日是天涯，望极天涯不见家 wrote:

 first, I'm try the POINTER to convesion the pointer type. but failed.
 
 class STUDENT(Structure):
 _fields_ = [('name',  c_int),
 ('id',   c_int),
 ('addition',c_ubyte)]
 
 buffer = c_byte * 1024
 student_p = cast(buffer, POINTER(STUDENT))
 
 The parameter of the POINTER must be ctypes type.
 How could I attach the buffer pointer to the structure STUDENT ?

I think it should work like this:

from ctypes import *

class STUDENT(Structure):
_fields_ = [('name',  c_int),
('id',   c_int),
('addition',c_ubyte)]

buffer = (c_byte * 1024)()
buffer_p = pointer(buffer)
student_p = cast(buffer_p, POINTER(STUDENT))

print student_p


Diez
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Re: ctypes: how to make a structure pointer to point to a buffer

[人言落日是天涯，望极天涯不见家]

On Apr 23, 5:42 pm, Diez B. Roggisch [EMAIL PROTECTED] wrote:
 人言落日是天涯，望极天涯不见家 wrote:
  first, I'm try the POINTER to convesion the pointer type. but failed.

  class STUDENT(Structure):
      _fields_ = [('name',  c_int),
                      ('id',   c_int),
                      ('addition',    c_ubyte)]

  buffer = c_byte * 1024
  student_p = cast(buffer, POINTER(STUDENT))

  The parameter of the POINTER must be ctypes type.
  How could I attach the buffer pointer to the structure STUDENT ?

 I think it should work like this:

 from ctypes import *

 class STUDENT(Structure):
     _fields_ = [('name',  c_int),
                     ('id',   c_int),
                     ('addition',    c_ubyte)]

 buffer = (c_byte * 1024)()
 buffer_p = pointer(buffer)
 student_p = cast(buffer_p, POINTER(STUDENT))

 print student_p

 Diez


yes, it should add the bracket
buffer = (c_byte * 1024)()

Thank you !

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