Golang: Read File

By Xah Lee. Date: . Last updated: .

Read Whole File

package main

import "fmt"
import "io/ioutil"

func main() {

    // read whole file
    myText, myErr := ioutil.ReadFile("/Users/x/filepath")

    if myErr != nil {
        panic(myErr)
        // panic means abort
    }

    // print it. String converts it to string
    fmt.Print(string(myText))

}

Read First X Bytes

package main

import "fmt"
import "os"

// open file. read first 200 bytes. print it.

var filePath = "/Users/xah/web/xahlee_info/golang/golang_read_file.html"

func getHeadBytes(path string, n int) []byte {

    file, err := os.Open(path) // For read access.
    if err != nil {
        panic(err)
    }

    defer file.Close()

    headBytes := make([]byte, n)
    m, err := file.Read(headBytes)
    if err != nil {
        panic(err)
    }

    return headBytes[:m]
}

func main() {

    fmt.Printf("%q\n", getHeadBytes(filePath, 200))

}

If you have a question, put $5 at patreon and message me.

Golang

  1. Compile, Run
  2. Package, Import
  3. Comment
  4. Print
  5. String
  6. Rune
  7. Variable
  8. Zero Value
  9. Constant
  10. If Then Else
  11. Switch/Case
  12. Loop
  13. Basic Types
  14. Array
  15. Slice
  16. Map
  17. Struct
  18. Function
  19. regexp
  20. Read File
  21. Write to File
  22. Walk Dir
  23. Check File Exist
  24. System Call
  25. Pointer
  26. Defer
  27. Random Number

Examples

  1. Validate Links
  2. Generate Sitemap

Reference

  1. Go Spec