+-
我有一个我通过ctypes访问的结构:
struct attrl {
char *name;
char *resource;
char *value;
struct attrl *next;
enum batch_op op;
};
到目前为止,我有Python代码,如:
# struct attropl
class attropl(Structure):
pass
attrl._fields_ = [
("next", POINTER(attropl)),
("name", c_char_p),
("resource", c_char_p),
("value", c_char_p),
但我不确定如何使用batch_op枚举.我应该将它映射到c_int还是?
最佳答案
至少对于GCC而言,枚举只是一种简单的数字类型.它可以是8,16,32,64位或其他(我用64位值测试过)以及有符号或无符号.我想它不能超过long long int,但实际上你应该检查你的枚举范围并选择类似c_uint的东西.
这是一个例子. C程序:
enum batch_op {
OP1 = 2,
OP2 = 3,
OP3 = -1,
};
struct attrl {
char *name;
struct attrl *next;
enum batch_op op;
};
void f(struct attrl *x) {
x->op = OP3;
}
和Python之一:
from ctypes import (Structure, c_char_p, c_uint, c_int,
POINTER, CDLL)
class AttrList(Structure): pass
AttrList._fields_ = [
('name', c_char_p),
('next', POINTER(AttrList)),
('op', c_int),
]
(OP1, OP2, OP3) = (2, 3, -1)
enum = CDLL('./libenum.so')
enum.f.argtypes = [POINTER(AttrList)]
enum.f.restype = None
a = AttrList(name=None, next=None, op=OP2)
assert a.op == OP2
enum.f(a)
assert a.op == OP3
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