golang compilation error: "undefined: regexp.MustCompile" How to solve it?

For programmers who are developing using Go language, compilation errors are commonplace. One of the common errors is: "undefined: regexp.MustCompile". This error usually occurs when trying to use the MustCompile function in your code while using the regexp package. This article will briefly describe the causes and solutions to this error.

Error reason

By default, the regexp package of Go language does not export the MustCompile function. This function is a method provided by the Regexp structure, so before using the MustCompile function, you need to use a regular expression and compile it into the Regexp structure . This structure contains information about the regular expression, such as the pattern string and matching options.

If you use the regexp.MustCompile function directly in your code, the Go compiler will throw an "undefined" error because the function is not actually in the regexp package in the top-level namespace. In other words, the compiler cannot find the definition of the function.

Solution

To solve this problem, you need to pass the regular expression string to be compiled to the Compile method of the Regexp structure. The Compile method returns a pointer of type *Regexp, which contains compiled regular expression information.

To make the code more concise, you can use a variant of the regexp.MustCompile function, as shown below:

func MustCompile(str string) *Regexp {
        regexp := Compile(str)
        if regexp == nil {
                panic("regexp: Compile(" + quote(str) + ") failed")
        }
        return regexp
}

This function accepts a string as a parameter, and It compiles to a regular expression and returns a pointer of type *Regexp. If compilation fails, it will throw a panic.

So, if you want to use the regexp.MustCompile function, just call it like this:

regex := regexp.MustCompile(`(?i)hellos+(w+)`)

Here, string "(?i) hellos (w )" is the regular expression you want to compile. In this example, we use (?i) to match case-insensitive, hello to match the literal text "hello", and s to match one or more space characters, (w) means matching one or more alphanumeric characters.

In short, if you encounter this "undefined: regexp.MustCompile" compilation error, please use the Compile method or the MustCompile function to compile regular expressions. , and stores its compilation result in a variable of type *Regexp.

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