C to Python Function

Question

hondros 25 Junior Poster

14 Years Ago

I have the following function (from windows.h) which I am trying to use the Python C API to allow python to call it. This is the function:

BOOL ReadConsoleOutputCharacter(
  HANDLE hConsoleOutput, (Type Handle to Change (use STD_OUTPUT))
  LPTSTR lpCharacter, (char pointer to store Characters read)
  DWORD nLength, (length to read)
  COORD dwReadCoord, (Type COORD to start reading at)
  LPDWORD lpNumberOfCharsRead (length actually read)

This is a function that uses it correctly:

#include <windows.h>
#include <iostream>
using namespace std;

int main()
{
    HANDLE hOut;
    char Letters[5];
    COORD Where;
    DWORD NumRead;
    int i;

    hOut = GetStdHandle(STD_OUTPUT_HANDLE);

    cout << "A line of little consequence." << endl;

    Where.X = 4;
    ReadConsoleOutputCharacter(hOut,
                               Letters,
                               5,
                               Where,
                               &NumRead);
    cout << "5 letters starting from (4,0) ";
    cout << endl;
	cin.get(); //To see output

    return 0;
}

This is the function that I have written to try to allow python to access it:

static PyObject *
WindowsH_ReadCharacters(PyObject *self, PyObject *args)
{
	int length;
	length = 1;
	int x;
	int y;
	
	if (!PyArg_ParseTuple(args, "iii", &length, &x, &y))
		return PyInt_FromLong(1);

	char read[60000]; //I know this is a large number, I'm not sure how much the user will need.
	char *_string;
	COORD position;
	position.X = x;
	position.Y = y;

	HANDLE hOut;
	hOut = GetStdHandle(STD_OUTPUT_HANDLE);

	ReadConsoleOutputCharacter(
		hOut,
		read,
		length,
		position,
		NULL);

	for(x = 0; x <= length; x++)
	{
		_string[x] = read[x];
	}



	return Py_BuildValue("s", _string);
}

Can anybody help me? Python crashes as soon as I call this. If anyone has a way that could make it better, please share, it'll help =]
And if a mod thinks this will do better in C/C++, please move it there

python

2 Contributors
8 Replies
344 Views
2 Days Discussion Span
Latest Post 14 Years Ago Latest Post by hondros

TrustyTony 888 pyMod

14 Years Ago

Use

[/B] for C part
[code=C]
#include <windows.h>
#include <iostream>
using namespace std;

int main()
{
HANDLE hOut;
char Letters[5];
COORD Where;
DWORD NumRead;
int i;

hOut = GetStdHandle(STD_OUTPUT_HANDLE);

cout << "A line of little consequence." << endl;

Where.X = 4;
ReadConsoleOutputCharacter(hOut,
Letters,
5,
Where,
&NumRead);
cout << "5 letters starting from (4,0) ";
cout << endl;
cin.get(); //To see output

return 0;
}

This is the function that I have written to try to allow python to access it:

static PyObject *
WindowsH_ReadCharacters(PyObject *self, PyObject *args)
{
int length;
length = 1;
int x;
int y;

if (!PyArg_ParseTuple(args, "iii", &length, &x, &y))
return PyInt_FromLong(1);

char read[60000]; //I know this is a large number, I'm not sure how much the user will need.
char *_string;
COORD position;
position.X = x;
position.Y = y;

HANDLE hOut;
hOut = GetStdHandle(STD_OUTPUT_HANDLE);

ReadConsoleOutputCharacter(
hOut,
read,
length,
position,
NULL);
for(x = 0; x <= length; x++)
{
_string[x] = read[x];
}


return Py_BuildValue("s", _string);
}

What is your Python code you wanted to access from C?

Edited 14 Years Ago by TrustyTony because: n/a

TrustyTony 888 pyMod

14 Years Ago

Did you check up this modulator.py thing mentioned in documentation:

A more substantial example module is included in the Python source distribution as Modules/xxmodule.c. This file may be used as a template or simply read as an example. The modulator.py script included in the source distribution or Windows install provides a simple graphical user interface for declaring the functions and objects which a module should implement, and can generate a template which can be filled in. The script lives in the Tools/modulator/ directory; see the README file there for more information.

Reply to this topic

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.

hondros 25 Junior Poster · Answer 1 · 2010-07-02T04:56:17+00:00

Thanks, thought it was something else. I want to be able to call it like this:

ReadCharacters(amount, x, y) -> 
   Read the amount of characters at position x, y;
   return a string with the characters

That will call this C funtion

BOOL ReadConsoleOutputCharacter(
HANDLE hConsoleOutput, (Type Handle to Change (use STD_OUTPUT))
LPTSTR lpCharacter, (char pointer to store Characters read)
DWORD nLength, (length to read)
COORD dwReadCoord, (Type COORD to start reading at)
LPDWORD lpNumberOfCharsRead (length actually read)

I'm having a big trouble with this one. I have a ton of other functions from windowsC.h that work. I realize there is win32Console, but it doesn't include all of the functions I need. I just need a C function that will allow me to use that function in Python.

hondros 25 Junior Poster · Answer 2 · 2010-07-03T02:01:01+00:00

I seem to not be able to find those files. Either in source or the build. I have a new dilemma. I was able to get the function to run through python, however, it now only returns a three character string of \x bits. Here's the code:

static PyObject *
WindowsH_ReadCharacters(PyObject *self, PyObject *args)
{
	DWORD length;
	int x;
	int y;
	
	if (!PyArg_ParseTuple(args, "iii", &length, &x, &y))
		return PyInt_FromLong(1);
	char* string=NULL;
	string = new char[length];
	COORD position;
	position.X = x;
	position.Y = y;

	HANDLE hOut;
	hOut = GetStdHandle(STD_OUTPUT_HANDLE);

	ReadConsoleOutputCharacter(
		hOut,
		string,
		length,
		position,
		NULL);

	return PyString_FromString(string);
}

* Note that the <string> header is not included in the source.

TrustyTony 888 pyMod Team Colleague Featured Poster · Answer 3 · 2010-07-03T02:55:57+00:00

I seem to not be able to find those files.

Modulator.py seems to exist in net at least in source files:
http://www.sfr-fresh.com/unix/misc/Python-2.6.5.tgz/

hondros 25 Junior Poster · Answer 4 · 2010-07-03T02:59:34+00:00

Right. I downloaded that package and I can't seem to find it.

TrustyTony 888 pyMod Team Colleague Featured Poster · Answer 5 · 2010-07-03T03:03:31+00:00

Right. I downloaded that package and I can't seem to find it.

drwxrwxr-x       0 2010-03-18 23:17 Python-2.6.5/Tools/modulator/
-rw-rw-r--    1360 2003-10-24 22:09 Python-2.6.5/Tools/modulator/EXAMPLE.py
-rwxrwxr-x    4824 2004-07-18 08:16 Python-2.6.5/Tools/modulator/genmodule.py
-rwxrwxr-x   14438 2004-07-18 08:16 Python-2.6.5/Tools/modulator/modulator.py
-rw-rw-r--     980 1999-02-16 18:19 Python-2.6.5/Tools/modulator/README
-rw-rw-r--    1477 2003-10-24 22:09 Python-2.6.5/Tools/modulator/ScrolledListbox.py
drwxrwxr-x       0 2010-03-18 23:17 Python-2.6.5/Tools/modulator/Templates/
-rw-rw-r--       0 2000-09-02 01:29 Python-2.6.5/Tools/modulator/Templates/copyright
-rw-rw-r--     113 1995-06-20 20:45 Python-2.6.5/Tools/modulator/Templates/mod
.................... etc ................................

hondros 25 Junior Poster · Answer 6 · 2010-07-03T03:13:48+00:00

Oh okay, I was looking in the wrong place xD
I'll take a look, thank you