How to install flask framework

Install the flask framework by opening a terminal or command prompt window, ensuring that Python is installed, creating a virtual environment, activating the virtual environment, installing Flask, verifying the installation, etc. Detailed introduction: 1. Open a terminal or command prompt window, whether it is feasible on Windows, Mac or Linux; 2. Make sure that Python is installed. You can download and install the latest version of Python from the official Python website; 3. Create a virtual environment and so on.

The operating system for this tutorial: Windows 10 system, Python version 3.11.4, DELL G3 computer.

To install the Flask framework, you can follow the steps below:

1. Open a terminal or command prompt window. Whether on Windows, Mac or Linux, you can execute commands by opening a Terminal or Command Prompt window.

2. Make sure you have installed Python. Flask is a Python-based framework, so before installing Flask, you need to install Python first. You can download and install the latest version of Python from the official Python website (https://www.python.org).

3. Create a virtual environment (optional). A virtual environment can isolate dependency packages required by different projects to prevent conflicts between them. Virtual environments are optional but highly recommended when developing Flask applications. You can create virtual environments using Python's built-in venv module. In a terminal or command prompt window, go to the directory where you want to create the virtual environment and execute the following command:

python -m venv myenv

This will create a virtual environment named "myenv".

4. Activate the virtual environment (optional). If you created a virtual environment, activate it in a terminal or command prompt window. Activating a virtual environment ensures that all commands you run in the terminal are associated with that environment. In Windows systems, you can execute the following command to activate the virtual environment:

myenv\Scripts\activate

In Unix-like systems (such as Linux and Mac), you can execute the following commands to activate the virtual environment:

source myenv/bin/activate

5. Installation Flask. With a virtual environment activated (if using a virtual environment) or a global Python environment, execute the following command to install Flask:

pip install flask

This will download and install the latest version of the Flask library and its dependencies.

6. Verify the installation. After the installation is complete, you can execute the following command to verify whether Flask is successfully installed:

flask --version

If the installation is successful, the terminal or command prompt window will display the installed Flask version number.

Now, you have successfully installed the Flask framework. You can start developing web applications using Flask. Here is a simple example:

from flask import Flask
# 创建Flask应用程序实例
app = Flask(__name__)
# 定义路由和视图函数
@app.route('/')
def hello():
return 'Hello, Flask!'
# 运行应用程序
if __name__ == '__main__':
app.run()

Save the above code as an app.py file and execute the following command in a terminal or command prompt window to run the application:

python app.py

Flask will A development server will be started locally and listen to the default port 5000. You can view the application's output by visiting http://localhost:5000 in your browser.

This is just the basic usage of the Flask framework. Flask also provides many powerful functions and extensions, such as route definition, template rendering, database integration, etc. You can refer to the official Flask documentation (https://flask.palletsprojects.com) for more details and sample code.

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