How Python is called in C/

The meaning of calling a Python script in C + + is no, at least you can think of it as a dynamic link library in textual form,

Need time can also change a change, as long as not change the interface, C + + program once compiled, and then change is not so convenient

Look at Python code first.

Code:

#test function def add (A, B): print "In Python function add" print "a =" + str (a) print "b =" + str (b) print "ret =" + str (A+B) Return def foo (a): print "In Python function foo" print "a =" + str (a) print "ret =" + str (A * a) Return

Save the Python code above as pytest.py

Next comes the code for C + +

Code:

#include "Python.h" int main (int argc, char** argv) { Initialize Python Before using a Python system, you must use Py_initialize to To initialize. It will load the Python built-in module and add the system path To the module search path. This function does not return a value, check the system The success of initialization requires the use of py_isinitialized. Py_initialize (); Check if initialization is successful if (! Py_isinitialized ()) { return-1; } Add Current Path Runs the input string directly as Python code, returning 0 Indicates success, 1 indicates an error. Most of the time the error is due to the string There is a syntax error in the. pyrun_simplestring ("Import sys"); Pyrun_simplestring ("Sys.path.append ('./')"); Pyobject *pname,*pmodule,*pdict,*pfunc,*pargs; Load a script named Pytest PName = pystring_fromstring ("Pytest"); Pmodule = Pyimport_import (pName); if (!pmodule) { printf ("Can ' t find pytest.py"); GetChar (); return-1; } Pdict = Pymodule_getdict (pmodule); if (!pdict) { return-1; } Find the function named add PFunc = pydict_getitemstring (pdict, "add"); if (!pfunc | |!) Pycallable_check (PFunc)) { printf ("Can ' t find function [Add]"); GetChar (); return-1; } parameter in stack *pargs; PArgs = Pytuple_new (2); pyobject* Py_buildvalue (char *format, ...) Convert C + + variables into a Python object. When needed from This function is used when C + + passes variables to python. This function A bit similar to C's printf, but in a different format. The commonly used formats are s represents a String, I represents an integer variable, F represents a floating-point number, O represents a Python object. Pytuple_setitem (PArgs, 0, Py_buildvalue ("L", 3)); Pytuple_setitem (PArgs, 1, Py_buildvalue ("L", 4)); Calling the Python function Pyobject_callobject (PFunc, PArgs); The following is the Find function foo and execute foo PFunc = pydict_getitemstring (pdict, "foo"); if (!pfunc | |!) Pycallable_check (PFunc)) { printf ("Can ' t find function [foo]"); GetChar (); return-1; } PArgs = pytuple_new (1); Pytuple_setitem (PArgs, 0, Py_buildvalue ("L", 2)); // Pyobject_callobject (PFunc, PArgs); Py_decref (PName); Py_decref (PArgs); Py_decref (Pmodule); Close Python Py_finalize (); return 0; }

Compile options, you need to manually specify Python's include path, and link path,

g++ Python.cpp-o python-i/usr/include/python2.5-l/usr/lib/python2.5-lpython2.5

How Python is called in C/