Solution: single counter

---

examples/counter-single/counter_single.go

package main

import (
    "bufio"
    "fmt"
    "os"
    "strconv"
)

func main() {
    var filename = "counter.txt"
    var cnt = 0
    var fhin, err1 = os.Open(filename)
    if err1 == nil {
        reader := bufio.NewReader(fhin)
        var line, _ = reader.ReadString('\n')
        cnt, _ = strconv.Atoi(line)
    }

    cnt++
    fmt.Println(cnt)

    var fhout, err2 = os.Create(filename)
    if err2 == nil {
        fhout.WriteString(fmt.Sprintf("%d", cnt))
        fhout.Close()
    }
}