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))

}

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Golang

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

Examples

  1. match any regexp
  2. Validate Links
  3. Generate Sitemap

Reference

  1. Go Spec