File Operations | File Handling

Introduction

File operations are a fundamental part of programming. Go (often referred to as Golang) provides robust support for file handling through its standard library. In this tutorial, we will cover various file operations including creating, reading, writing, and closing files in Go.

Creating and Opening Files

In Go, you can create and open files using the os package. The os.Create() function is used to create a new file or truncate an existing file. The os.Open() function is used to open an existing file for reading.

package main

import (
    "fmt"
    "os"
)

func main() {
    // Create a new file
    file, err := os.Create("example.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println("File created successfully")
    file.Close()

    // Open the existing file
    file, err = os.Open("example.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println("File opened successfully")
    file.Close()
}

Writing to a File

Once you have created or opened a file, you can write to it using the Write or WriteString methods.

package main

import (
    "fmt"
    "os"
)

func main() {
    // Create a new file
    file, err := os.Create("example.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer file.Close()

    // Write to the file
    bytesWritten, err := file.Write([]byte("Hello, Go!"))
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Printf("Bytes written: %d\n", bytesWritten)
}

Reading from a File

To read from a file, you can use the Read or ReadAll methods from the os or io/ioutil packages.

package main

import (
    "fmt"
    "io/ioutil"
    "os"
)

func main() {
    // Open the existing file
    file, err := os.Open("example.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer file.Close()

    // Read from the file
    data, err := ioutil.ReadAll(file)
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Printf("File contents: %s\n", data)
}

Closing Files

It is essential to close a file after completing the operations on it to release the resources. This is done using the Close method.

package main

import (
    "fmt"
    "os"
)

func main() {
    // Create a new file
    file, err := os.Create("example.txt")
    if err != nil {
        fmt.Println(err)
        return
    }

    // Ensure the file is closed at the end
    defer file.Close()

    fmt.Println("File operations completed successfully")
}

Checking File Existence

Before performing file operations, it might be useful to check if a file exists. This can be done using os.Stat().

package main

import (
    "fmt"
    "os"
)

func main() {
    _, err := os.Stat("example.txt")
    if os.IsNotExist(err) {
        fmt.Println("File does not exist")
    } else {
        fmt.Println("File exists")
    }
}

Deleting a File

You can delete a file using the os.Remove() function.

package main

import (
    "fmt"
    "os"
)

func main() {
    // Delete the file
    err := os.Remove("example.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println("File deleted successfully")
}

File Operations in Go Programming