[英]How to return a pointer to a structure in ctypes?
I try to pass a pointer of a structure which is given me as a return value from the function 'bar' to the function 'foo_write'. 我尝试传递一个结构的指针,该结构从函数'bar'返回给函数'foo_write'作为返回值。 But I get the error message 'TypeError: must be a ctypes type' for line 'foo = POINTER(temp_foo)'.
但是我得到'foo = POINTER(temp_foo)'行的错误消息'TypeError:必须是ctypes类型'。 In the ctypes online help I found that 'ctypes.POINTER' only works with ctypes types.
在ctypes在线帮助中,我发现'ctypes.POINTER'仅适用于ctypes类型。 Do you know of another way?
你知道另一种方式吗? What would you recommend?
你会推荐什么?
C: C:
typedef struct FOO_{
int i;
float *b1;
float (*w1)[];
}FOO;
foo *bar(int foo_parameter) {...
void foo_write(FOO *foo)
Python with ctypes: Python与ctypes:
class foo(Structure):
_fields_=[("i",c_int),
("b1",POINTER(c_int)),
("w1",POINTER(c_float))]
temp_foo=foo(0,None,None)
foo = POINTER(temp_foo)
foo=myclib.bar(foo_parameter)
myclib.foo_write(foo)
Change 更改
foo = POINTER(temp_foo)
to 至
foo = pointer(temp_foo)
can solve the problem. 可以解决问题。
Please see http://docs.python.org/library/ctypes.html#ctypes-pointers for more information. 有关更多信息,请参阅http://docs.python.org/library/ctypes.html#ctypes-pointers 。
Your bar
function has an incorrect definition, I guess you mean it is struct FOO_ *bar(int);
你的
bar
函数有一个不正确的定义,我猜你的意思是它是struct FOO_ *bar(int);
? ?
The Python code is wrong in the sense that foo_parameter
is never declared, so I'm not 100% sure what you want to do. 从未声明
foo_parameter
的意义上的Python代码是错误的,所以我不能100%确定你想要做什么。 I assume you want to pass a parameter of your python-declared foo
, which is an instance of a struct FOO_
, into the C bar(int)
and get back a pointer to struct FOO_
. 我假设您要将python声明的
foo
的参数(它是struct FOO_
一个实例) struct FOO_
到C bar(int)
并返回指向struct FOO_
的指针。
You don't need POINTER to do that, the following will work: 您不需要POINTER来执行此操作,以下操作:
#!/usr/bin/env python
from ctypes import *
class foo(Structure):
_fields_=[("i",c_int),
("b1",POINTER(c_int)),
("w1",POINTER(c_float))]
myclib = cdll.LoadLibrary("./libexample.so")
temp_foo = foo(1,None,None)
foovar = myclib.bar(temp_foo.i)
myclib.foo_write(foovar)
Since CTypes will wrap the return type of bar()
in a pointer-to-struct for you. 因为CTypes会将指向结构的返回类型
bar()
包装回来。
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