How to use regular expressions to verify the legality of file extensions in golang

As golang becomes more and more widely used in application development, more and more developers are beginning to explore its powerful features, including how to use regular expressions to verify the legality of file extensions in golang. This article will introduce you how to use golang to achieve this function.

First, we need to understand regular expressions (regexp). Regular expressions are a method of describing text patterns, consisting of a sequence of characters and special symbols, used to match and process strings. In golang, you can use the built-in regexp package to create and manipulate regular expressions.

We know that in computer systems, file extensions refer to the part after the period in the file name. Therefore, verifying the validity of a file extension is equivalent to verifying that the file name ends with a period and one or more alphanumeric characters. We can use regular expressions to match this pattern.

The following is an example showing how to use the regexp package to achieve matching:

import "regexp"

func isValidExtension(filename string) bool {
    re := regexp.MustCompile(`.[a-zA-Z0-9]+$`)
    return re.MatchString(filename)
}

In this example, we use the regexp.MustCompile() function to create and compile a regular expression , which contains a pattern ending with a period and one or more alphanumeric characters. We then use the re.MatchString() function to test whether the file name matches this pattern, and if so, return true, otherwise return false.

The following is a complete sample program that demonstrates how to use the isValidExtension function to verify whether a file name has a legal extension:

package main

import (
    "fmt"
    "regexp"
)

func isValidExtension(filename string) bool {
    re := regexp.MustCompile(`.[a-zA-Z0-9]+$`)
    return re.MatchString(filename)
}

func main() {
    filenames := []string{"example.txt", "file", "myfile.docx", "picture.jpg"}

    for _, filename := range filenames {
        if isValidExtension(filename) {
            fmt.Printf("%s has a valid extension.
", filename)
        } else {
            fmt.Printf("%s has an invalid extension.
", filename)
        }
    }
}

In this sample program, we define a string slice filenames, which contains four file names. Then, we use a for loop to traverse the slice, call the isValidExtension() function on each file name to verify, and output the corresponding results. In this example, only example.txt and myfile.docx have valid extensions. This shows that our validation function successfully filters out legal and illegal file extensions.

So far, we have learned how to use the regexp package in golang to verify the legality of file extensions. Using regular expressions, we can easily match and filter file names, improving program efficiency and readability. Hope this article helps you!

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