3 ways to read files in Go
10 Apr 2020A quick reference for reading files in Go.
1. Simple file reading
For a simple file reading, let’s say when you just want to read it into a variable, you can use the ioutil library. The code blow demonstrates this.
import "io/ioutil"
func main() {
data, err := ioutil.ReadFile("foo.txt");
if err != nil {
return // error
}
// store data in a string
var text string = string(data);
}
2. Byte sized pieces
Another common way to read files in are in bite sized pieces. You would use this technique if your file is so large that reading it all in at once would be very very slow or crash your program. This is often known as streaming in data.
import (
"os"
"bufio"
)
func main() {
f, err := os.Open("foo.txt")
if err != nil {
// err
}
defer f.Close()
r := bufio.NewReader(f)
b := make([]byte, 4) // size of chunk
finalString = ""
for {
n, err := r.Read(b)
if err != nil {
break
}
finalString += string(b[0:n])
}
}