How to understand the running process of python program?

The content of this article is about how to understand the running process of python program? It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Understanding the execution process of the code is a basic requirement of programming. A skilled programming veteran only needs to look at the code with the naked eye to understand the process of its operation. However, for newcomers who have just started programming, this kind of thing is not so obvious. So when writing and debugging code, once the logic of the program is a little complicated, it's like falling into a maze of code, and you don't know what's going on.

So, whenever someone is puzzled that their code does not give the expected results and has no choice but to ask for help, I will suggest adding output to the program. On the one hand, it is based on the order of different outputs. To determine the running path of the program, on the other hand, it is to observe the actual values ​​of each variable during the running process to confirm where the error occurred.

Another method is to use the debugging function provided by the IDE to understand the running status of the program by adding breakpoints and single-step running. Almost all common IDEs such as Visual Studio, Eclipse, and xCode provide debugging tools. For Python, you can also use the pdb library to implement breakpoint debugging.

The above two methods should be the basic routine for most programmers when debugging. But again, for novices, even such a tool is still a bit laborious to use.

Sometimes I choose to draw some processes and graphics on paper to explain the program to people. Although the effect will be better, it is obviously not a way that can be widely promoted. Later, I accidentally discovered that there is a tool that meets such needs. It is very suitable for novices and allows you to intuitively "see" how the program runs. For those who are new to programming and have difficulty understanding the running process of the program, it can definitely be called an "artifact".

This is Online Python Tutor. A free online code running and demonstration tool.

Project address: pythontutor.com

Introduction to this project (taken from the Internet, source unknown):

Online Python Tutor is developed by Philip Guo A free educational tool developed to help students overcome basic obstacles in programming learning and understand the process of each line of source code in the computer when the program is executed. Through this tool, teachers or students can directly Write Python code in a web browser and visually execute the program step by step.

As of December 2013, a total of 50 people from 165 countries and regions More than 10,000 people have used this online tool, often as a supplement to textbooks, handouts, or online programming guides. Execute and demonstrate over 6,000 Python snippets every day program. In addition to self-taught beginners, Online Python Tutor users include those taking courses at Coursera, edX, and Udacity Students waiting for online courses, as well as teachers from universities such as MIT and UC Berkeley.

• Python Tutor supports both versions of Python 2.7 and 3.3.

• In addition to Python, it can also run Java, JavaScript, TypeScript, and Ruby. There are also versions that support C and C.

• You can embed this tool into your own page through a line of JS code.

• You can also generate links to share your code directly with others.

• Comes with unit testing capabilities.

• The website also provides many examples, including some classic algorithms.

Let’s experience its usage process again:

Enter the code in the editor and click “Visualize Execution” to run and demonstrate.

import random

def fn(x):
    return x**2

result = []
for i in range(3):
    t = random.randint(1, 10)
    print t
    r = fn(t)
    result.append(r)
print result

I used a code snippet containing loops, lists, functions, and modules. Take a look at the effect:

The upper left is the code, and the arrow indicates the current running position.

You can directly control the progress of the program through the buttons and progress bar below.

The lower left is the output.

The right side is the visual simulation of the program. In this example, you can clearly see the changes in variables during the process, when the function was called, and other information.

However, like many online running environments, Python Tutor does not support the input function during running. So we can't put our number guessing or penalty kick mini-games directly on it. Hope this feature can be added in the future.

With the help of Python Tutor, some algorithms can be understood more easily. Finally, put an implementation of bubble sorting, [](http://crossin-forum.b0.upaiy...

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