How to Uncompress a File in Golang?

In today's world of technology, compressing files has become an essential part of daily life. It not only helps to save disk space but also speeds up file transfers. However, at times, it becomes necessary to uncompress these files to extract the data inside. In this article, we will discuss how to uncompress a file in Golang, a popular programming language.

Step 1: Importing the Necessary Packages

Before we can start uncompressing files, we need to import the necessary packages. Golang comes with a built-in "compress" package that provides support for various compression algorithms. To uncompress files, we need to import the "compress/gzip" package.

import (
   "compress/gzip"
   "fmt"
   "os"
)

Step 2: Opening the Compressed File

Once we have imported the necessary packages, the next step is to open the compressed file. We can use the "os.Open" function to open the file and check for any errors.

file, err := os.Open("compressed_file.gz")
if err != nil {
   fmt.Println(err)
   return
}
defer file.Close()

Step 3: Creating a Gzip Reader

Now that we have opened the compressed file, the next step is to create a gzip reader using the "gzip.NewReader" function. This function takes in the file as an argument and returns a pointer to a gzip reader.

reader, err := gzip.NewReader(file)
if err != nil {
   fmt.Println(err)
   return
}
defer reader.Close()

Step 4: Reading the Uncompressed Data

The final step is to read the uncompressed data from the gzip reader. We can use the "io.Copy" function to copy the data from the gzip reader to a new file.

outFile, err := os.Create("uncompressed_file.txt")
if err != nil {
   fmt.Println(err)
   return
}
defer outFile.Close()

_, err = io.Copy(outFile, reader)
if err != nil {
   fmt.Println(err)
   return
}

Example

Here is the complete code −

package main

import (
   "compress/gzip"
   "fmt"
   "io"
   "os"
)

func main() {
   // Step 1: Opening the compressed file
   file, err := os.Open("compressed_file.gz")
   if err != nil {
      fmt.Println(err)
      return
   }
   defer file.Close()
   
   // Step 2: Creating a gzip reader
   reader, err := gzip.NewReader(file)
   if err != nil {
      fmt.Println(err)
      return
   }
   defer reader.Close()
   
   // Step 3: Reading the uncompressed data
   outFile, err := os.Create("uncompressed_file.txt")
   if err != nil {
      fmt.Println(err)
      return
   }
   defer outFile.Close()
   
   _, err = io.Copy(outFile, reader)
   if err != nil {
      fmt.Println(err)
      return
   }
   fmt.Println("File uncompressed successfully!")
}

Note − Replace the file names with the actual names of the compressed and uncompressed files you are working with.

Conclusion

In this article, we discussed how to uncompress a file in Golang using the "compress/gzip" package. The process involves importing the necessary packages, opening the compressed file, creating a gzip reader, and reading the uncompressed data. By following these simple steps, you can easily uncompress any compressed file in Golang.

Sabid Ansari

e

Updated on: 26-Apr-2023

564 Views

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