C calls Python

 

CMediumCallPython

# Include <Python. H>

Int main (INT argc, char * argv [])

{

Py_initialize ();

Pyrun_simplestring ("From time import time, ctime/N"

"Print 'Today is ', ctime (Time ()/n ");

Py_finalize ();

Return 0;

}

 

 

 

 

 

0. Bad Environment Settings
Add the include/libs directory of python to include/lib directories of VC respectively. In addition, Python does not provide debug Lib. Specifically, Python does not provide python25_d.lib. You can compile Python source code to obtain python25_d.lib. I have not tried it yet. And I did not download it after I found it online. Therefore, if you want to run the program in debug, you need to set pyconfig. H (in the python25/include/directory) is probably in the 283 line, change Pragma comment (Lib, "python25_d.lib") to Pragma comment (Lib, "python25.lib "), make Python use non-Debug Lib.

1. Programming started.
# Include <python. h>
The first step is to include the python header file.

2. Let's look at a simple example.
1) the python file test. py defines a function very easily.

# Filename test. py
Def Hello ():
Print "Hello, world! "

Should this be understandable? Otherwise, go back and practice python. Simple Python tutorial, by swaroop, C. H. Translated by Shen jieyuan.

2) CPP File

# Include <python. h> // contains the header file. It is required to embed python in C ++.
Int main ()
{
Py_initialize ();

Pyobject * pmodule = NULL;
Pyobject * pfunc = NULL;

Pmodule = pyimport_importmodule ("test ");
Pfunc = pyobject_getattrstring (pmodule, "hello ");
Pyeval_callobject (pfunc, null );

Py_finalize ();

Return 0;
}

The first step is to include the header file.

Step 2: Before using python, call py_initialize (); to initialize the function.
For example:
The basic initialization function is py_initialize (). this initializes the table of loaded modules, and creates the fundamental modules _ builtin __, _ main __, sys, and exceptions. it also initializes the module search path (sys. path ).

You must call it at the beginning.

Step 3: declare Python variables of the pyobject type. In fact, the statement can also be put in front of it. It doesn't matter.

Step 4: import module, that is, your script name. You do not need to add a suffix. Otherwise, errors will occur.

Step 5: Obtain the function from the module you import.
Pfunc = pyobject_getattrstring (pmodule, "hello ");
The above example is clear enough. The last one is the name of the function you want to obtain.

Step 6: Call pyeval_callobject to execute your function. The second parameter is the function of the function to be called. This example does not contain parameters, so it is set to null.

Step 7: Call py_finalize, which corresponds to py_initialize. One is at the beginning and the other is at the end.

 

 

 

 

 

 

The Code is as follows, which demonstrates the direct execution of Python statements, no return of non-parameter function calls, and the return of Single-Parameter Function calls. Return multi-parameter function call:

# Include <python. h>
# Include <iostream>
Using namespace STD;

// Execute the python command
Void execpythoncommand ()
{
// Directly execute
Pyrun_simplestring ("From time import time, ctime/N"
"Print 'Today is ', ctime (Time ()/n ");
}

// Call a function without Parameters
Void invokenoparm ()
{
Pyobject * pmod = NULL;
Pyobject * pfunc = NULL;
// Import module
Pmod = pyimport_importmodule ("life ");
If (pmod)
{
// Obtain the function address
Pfunc = pyobject_getattrstring (pmod, "");
If (pfunc)
{
// Function call
Pyeval_callobject (pfunc, null );
}
Else
{
Cout <"cannot find function a" <Endl;
}
}
Else
{
Cout <"cannot find life. py" <Endl;
}
}

// Call a Parameter Function
Void invokewith1parm ()
{
Pyobject * pmod = NULL;
Pyobject * pfunc = NULL;
Pyobject * pparm = NULL;
Pyobject * pretval = NULL;
Int iretval = 0;
// Import module
Pmod = pyimport_importmodule ("funcdef ");
If (pmod)
{
Pfunc = pyobject_getattrstring (pmod, "square ");
If (pfunc)
{
// Create parameters
Pparm = py_buildvalue ("(I)", 5 );
// Function call
Pretval = pyeval_callobject (pfunc, pparm );
// Parse the return value
Pyarg_parse (pretval, "I", & iretval );
Cout <"square 5 is:" <iretval <Endl;
}
Else
{
Cout <"cannot find Function Square" <Endl;
}
}
Else
{
Cout <"cannot find funcdef. py" <Endl;
}
}

// Call a multi-parameter Function
Void invokewith2parm ()
{
Pyobject * pmod = NULL;
Pyobject * pfunc = NULL;
Pyobject * pparm = NULL;
Pyobject * pretval = NULL;
Int iretval = 0;
// Import module
Pmod = pyimport_importmodule ("add ");
If (pmod)
{
Pfunc = pyobject_getattrstring (pmod, "add ");
If (pfunc)
{
// Create two parameters
Pparm = pytuple_new (2 );
// Assign values to parameters
Pytuple_setitem (pparm, 0, py_buildvalue ("I", 2000 ));
Pytuple_setitem (pparm, 1, py_buildvalue ("I", 3000 ));
// Function call
Pretval = pyeval_callobject (pfunc, pparm );
// Parse the return value
Pyarg_parse (pretval, "I", & iretval );
Cout <"2000 + 3000 =" <iretval <Endl;
}
Else
{
Cout <"cannot find Function Square" <Endl;
}
}
Else
{
Cout <"cannot find Add. py" <Endl;
}
}

Int main (INT argc, char * argv [])
{
Py_initialize (); // Python interpreter Initialization

Execpythoncommand ();
Invokenoparm ();
Invokewith1parm ();
Invokewith2parm ();

Py_finalize (); // garbage collection, clear import/export warehouse
Return 0;
}