Question

我无法弄清楚如何编组指向python和C之间的c-string的指针。我试图用签名包装现有的库：

int connect(char* url, char** host, char** port, char** path);

connect函数设置主机，端口和路径。网址参数很好，但是双指针引起了麻烦。

我需要在我的.i文件中放置什么才能正确地编组双指针？

Answer 1

如果char**参数仅为输出，则以下内容将起作用。由于未指定实现，因此我将malloc返回的参数并假设为ASCII / UTF-8字符串。我还假设Python 3。

%module x

%{
#include <stdlib.h>
#include <stdio.h>
%}

%include <exception.i>

// This makes char** output-only and it won't be a required parameter in the
// Python interface.  A temporary char* is created for each char** encountered
// and its address is used for the char** parameter.
%typemap(in,numinputs=0) char** (char* tmp) %{
    $1 = &tmp;
%}

// This typemap is processed after calling the function.
// It converts the returned value to a Python Unicode string.
// The malloc'ed return value is no longer needed so is freed.
%typemap(argout) char** (PyObject* tmp) %{
    tmp = PyUnicode_FromString(*$1);
    $result = SWIG_Python_AppendOutput($result,tmp);
    free(*$1);
%}

%inline %{
int connect(char* url, char** host, char** port, char** path)
{
    *host = malloc(10);
    *port = malloc(10);
    *path = malloc(10);
    strcpy(*host,"host");
    strcpy(*port,"port");
    strcpy(*path,"path");
    return 1;
}
%}

演示：

>>> import x
>>> x.connect('url')
[1, 'host', 'port', 'path']

如何通过SWIG编组指向Python和C之间的cstring的指针

1 个答案: