Shulou(Shulou.com)06/02 Report--

In this issue, the editor will bring you about how to understand the two commonly used functions embedded in Python at a lower level. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

If you need to use a Python script to pass parameters in a C program, or get the return value of a Python script, you need to use more functions to write a C program. Because Python has its own data type, it is necessary to use a special API to manipulate the corresponding data type in C program. The following functions are commonly used.

1. Number and string processing

The Py_BuildValue () function is provided in Python/C API to convert numbers and strings to the corresponding data types in Python. The function prototype is shown below.

PyObject* Py_BuildValue (const char * format,...)

The meaning of the parameters is as follows.

Format: format the string, as shown in Table 8-1.

Py_BuildValue ()

The remaining parameters in the function are integers, floating-point types, or strings in the C language to be converted. The return value is a PyObject pointer. In the C language, all Python types are declared as Pyobject types.

2. List operation

The PyList_New () function is provided in Python/C API to create a new Python list. The return value of the PyList_New () function is the list you created. The function prototype is shown below.

PyObject* PyList_New (Py_ssize_t len)

The meaning of the parameters is as follows.

Len: the length of the list created.

After the list is created, you can use the PyList_SetItem () function to add items to the list. The function prototype is shown below.

Int PyList_SetItem (PyObject * list

Py_ssize_t index, PyObject * item)

The meaning of the parameters is as follows.

List: a list of items to add.

Index: the location index of the item being added.

Item: the value of the item being added.

You can also use the PyList_GetItem () function in Python/C API to get the value of an item in the list. The PyList_GetItem () function returns the value of the item. The function prototype is shown below.

PyObject* PyList_GetItem

(PyObject * list, Py_ssize_t index)

The above is the editor for you to share how to understand Python embedded in the lower level of the two commonly used functions, if you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.