[英]C++ boost.python cannot convert const char* to str
I want to calculate something in C++ and return result to python. 我想用C ++计算一些东西并将结果返回给python。 This is part of the C++ code:
这是C ++代码的一部分:
const Mat& flow_map_x, flow_map_y;
std::vector<unchar> encoded_x, encoded_y;
flow_map_x = ...;
flow_map_y = ...;
Mat flow_img_x(flow_map_x.size(), CV_8UC1);
Mat flow_img_y(flow_map_y.size(), CV_8UC1);
encoded_x.resize(flow_img_x.total());
encoded_y.resize(flow_img_y.total());
memcpy(encoded_x.data(), flow_img_x.data, flow_img_x.total());
memcpy(encoded_y.data(), flow_img_y.data, flow_img_y.total());
bp::str tmp = bp::str((const char*) encoded_x.data())
The error when running python script is: 运行python脚本时的错误是:
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x80 in position 0: invalid start byte
After debugging, I found that the error comes from this line: 调试后,我发现错误来自此行:
bp::str tmp = bp::str((const char*) encoded_x.data())
I'm not good at C++. 我不擅长C ++。 Could anyone tell me how to fix the error?
谁能告诉我如何解决该错误? Thanks in advance!
提前致谢!
You can't because encoded_x.data()
is not UTF-8. 你不能因为
encoded_x.data()
不是UTF-8。 You probably want bytes
for a copy of the raw data: 您可能需要
bytes
用于原始数据的副本:
Using PyObject * PyBytes_FromStringAndSize (const char * v , Py_ssize_t len )
. 使用
PyObject * PyBytes_FromStringAndSize (const char * v , Py_ssize_t len )
。 Or you can use PyByteArray_FromStringAndSize
for a bytearray
with the same arguments. 或者你可以使用
PyByteArray_FromStringAndSize
一个bytearray
具有相同的参数。
bp::object tmp(bp::handle<>(PyBytes_FromStringAndSize(
// Data to make `bytes` object from
reinterpret_cast<const char*>(encoded_x.data()),
// Amount of data to read
static_cast<Py_ssize_t>(encoded_x.size())
)));
In this case, you can get rid of the vector and use flow_img_x.data
and flow_img_x.total()
directly. 在这种情况下,您可以删除向量并直接使用
flow_img_x.data
和flow_img_x.total()
。
Or a memoryview
to not copy the data, but just access the std::vector
s data 或者是一个不复制数据的
memoryview
,只是访问std::vector
的数据
Using PyObject* PyMemoryView_FromMemory (char * mem , Py_ssize_t size , int flags )
使用
PyObject* PyMemoryView_FromMemory (char * mem , Py_ssize_t size , int flags )
bp::object tmp(bp::handle<>(PyMemoryView_FromMemory(
reinterpret_cast<char*>(encoded_x.data()),
static_cast<Py_ssize_t>(encoded_x.size()),
PyBUF_WRITE // Or `PyBUF_READ` i if you want a read-only view
)));
(If the vector was const, you would const_cast<char*>(reinterpret_cast<const char*>(encoded_x.data()))
and only use PyBUF_READ
) (如果向量是const,则将
const_cast<char*>(reinterpret_cast<const char*>(encoded_x.data()))
,仅使用PyBUF_READ
)
You have to make sure the vector stays alive in this case though, but it won't create an unnecessary copy. 在这种情况下,您必须确保向量仍然有效,但是不会创建不必要的副本。
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