Regular expressions (regex) is not an easy topic and many people just ignore its existence until met with the necessity to use them. I heard many times the phrase “If you have a problem and you use regular expressions to solve that problem, then you have two problems.” and I really hate it. I then realized that people who say that are the people who do not know how to write proper regular expressions.
正则表达式（regex）不是一个容易的话题，许多人只是忽略了它的存在，直到有必要使用它们。我听过很多次这样一句话：“如果你有一个问题，你用正则表达式来解决这个问题，那么你就有两个问题。然后我意识到，说这些话的人是不知道如何编写正确的正则表达式的人。

That is why I’m sharing the knowledge on the most important concepts of regex. After you grasp them, writing regular expressions will become quite easy, but the most important part is that YOU WILL SAVE AN INCREDIBLE AMOUNT OF TIME using regex. Tasks that took 1 hour to complete, now might take minutes or even seconds. With practice, the amount of time you save for yourself will be increasing.
这就是为什么我要分享有关正则表达式最重要概念的知识。掌握它们后，编写正则表达式将变得非常容易，但最重要的部分是使用正则表达式将节省大量时间。需要 1 小时才能完成的任务，现在可能需要几分钟甚至几秒钟。通过练习，您为自己节省的时间会增加。

That is why this course is very practical and will focus on real-life examples. It is appropriate for any knowledge level: beginner, intermediate or advanced and contains regular expressions cheat sheets. The content is also divided into three levels: Basic, Intermediate, and Advanced. In each of those levels, increasingly difficult regular expression concepts will be discussed in a practical manner through exercises. We will always be focusing on how we can write and apply our regular expressions to real-life examples so when you finish the course, you will have the experience required to write any regular expression you might need. And there are more than 45 examples that will help you with that!
这就是为什么本课程非常实用，并将侧重于现实生活中的例子。它适用于任何知识水平：初级、中级或高级，并包含正则表达式备忘单。内容也分为三个级别：初级、中级和高级。在每个级别中，将通过练习以实际的方式讨论越来越难的正则表达式概念。我们将始终专注于如何编写正则表达式并将其应用于现实生活中的示例，因此当您完成课程时，您将拥有编写可能需要的任何正则表达式所需的经验。有超过 45 个示例可以帮助您！

You will learn: 您将学习：
– regular expressions basics;
– 正则表达式基础;

– regular expressions quantifiers (number of characters): ranges, at least one, one or none, etc.;
– 正则表达式量词（字符数）：范围、至少一个、一个或无等;

– regular expressions shortcuts through character classes and groups;
– 正则表达式：字符类和组的快捷方式;

– regular expressions alternation;
– 正则表达式交替;

– regular expressions parenthesis and how they are used for in easy and complex situations;
– 正则表达式括号以及它们在简单和复杂情况下的使用方式;

– regular expressions lookaround: lookahead and lookbehind.
– 正则表达式 lookaround：lookahead 和 lookbehind。

You will practice and learn how to write:
您将练习并学习如何写作：

– regular expressions for URL validation;
– 用于 URL 验证的正则表达式;

– regular expressions for password validation;
– 用于密码验证的正则表达式;

– regular expressions for numeric data validation and extraction;
– 用于数值数据验证和提取的正则表达式;

AND MUCH MORE! 还有更多！
 
The course can be used to apply the regular expressions in Python, Java, Javascript, Golang, C, C#, or any other programming language. What you will learn is also applicable outside the programming languages. Any tool that supports regular expressions will allow you to benefit from this course. Think about regular expressions for grep, excel, or even google analytics. The regular expressions cheat sheets that are provided at the end of each section will help you to hold the knowledge outside the course!
该课程可用于在 Python、Java、Javascript、Golang、C、C# 或任何其他编程语言中应用正则表达式。您将学到的知识也适用于编程语言之外。任何支持正则表达式的工具都可以让您从本课程中受益。想想 grep、excel 甚至 google analytics 的正则表达式。每个部分末尾提供的正则表达式备忘单将帮助您在课程之外掌握知识！