Read text file into string array (and write)

The ability to read (and write) a text file into and out of a string array is I believe a fairly common requirement. It is also quite useful when starting with a language removing the need initially to access a database. Does one exist in Golang?
e.g.

func ReadLines(sFileName string, iMinLines int) ([]string, bool) {

and

func WriteLines(saBuff[]string, sFilename string) (bool) { 

I would prefer to use an existing one rather than duplicate.

Solution 1:

As of Go1.1 release, there is a bufio.Scanner API that can easily read lines from a file. Consider the following example from above, rewritten with Scanner:

package main

import (
    "bufio"
    "fmt"
    "log"
    "os"
)

// readLines reads a whole file into memory
// and returns a slice of its lines.
func readLines(path string) ([]string, error) {
    file, err := os.Open(path)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    var lines []string
    scanner := bufio.NewScanner(file)
    for scanner.Scan() {
        lines = append(lines, scanner.Text())
    }
    return lines, scanner.Err()
}

// writeLines writes the lines to the given file.
func writeLines(lines []string, path string) error {
    file, err := os.Create(path)
    if err != nil {
        return err
    }
    defer file.Close()

    w := bufio.NewWriter(file)
    for _, line := range lines {
        fmt.Fprintln(w, line)
    }
    return w.Flush()
}

func main() {
    lines, err := readLines("foo.in.txt")
    if err != nil {
        log.Fatalf("readLines: %s", err)
    }
    for i, line := range lines {
        fmt.Println(i, line)
    }

    if err := writeLines(lines, "foo.out.txt"); err != nil {
        log.Fatalf("writeLines: %s", err)
    }
}

Solution 2:

Note: ioutil is deprecated as of Go 1.16.

If the file isn't too large, this can be done with the ioutil.ReadFile and strings.Split functions like so:

content, err := ioutil.ReadFile(filename)
if err != nil {
    //Do something
}
lines := strings.Split(string(content), "\n")

You can read the documentation on ioutil and strings packages.