11-data-io.md

Data IO in Go

Table of Contents:

• Data IO in Go
  • 1. IO with readers and writers
  • 2. Formatted IO with fmts
  • 3. Buffered IO
  • 4. In-memory IO

1. IO with readers and writers

Go models data input and output as a stream that flows from sources to targets. Data sources, such as files, network connections, or even some in-memory objects, can be modeled as streams of bytes from which data can be read or written to.

2. Formatted IO with fmts

The most common usage of the fmt package is for writting to standard output and reading from standard input.

type metalloid struct {
    name string
    number int32
    weight float64
}

func main() {
    var metalloids = []metalloid{
        {"Boron", 5, 10.81},
         ...
         {"Polonium", 84, 209.0},
    }
     file, _ := os.Create("./metalloids.txt")
     defer file.Close()
     for _, m := range metalloids {
        fmt.Fprintf(
            file,
            "%-10s %-10d %-10.3f\n",
            m.name, m.number, m.weight,
        )
     }
}

3. Buffered IO

The bufio package offers several functions to do buffered writing of IO streams using an `io.Writer interface.

4. In-memory IO

In bytes package offers common primitives to achieve streaming IO on blocks of bytes stored in memory, represented by the bytes.Buffer byte. Since the bytes.Buffer type implements both io.Reader and io.Writer interfaces it is a great option to stream data into or out of memory using streaming IO primitives.