Need Help in conversion of time into seconds which can handle with hours and without hours in Golang

want to change time duration is seconds but don't want to give hours every time (hrs as optional)

package main

import (
    "fmt"
)

func main() {
  t1 := "01:30"
  seconds, _ := ConvertTimeFormat(t1) // not working fine for this
  fmt.Println(seconds)

   t2 := "01:01:15"
   second, _ := ConvertTimeFormat(t2) // working fine for this
   fmt.Println(second)
}

func ConvertTimeFormat(st string) (int, error) {
    var h, m, s int
    n, err := fmt.Sscanf(st, "%d:%d:%d", &h, &m, &s)
    fmt.Print(n, err)
    if err != nil || n != 3 {
        return 0, err  
    }
    return h*3600 + m*60 + s, nil
}

Your code is buggy, since you always expect 3 values in the Scanf func.

Try to parse it another way, like:

package main
import (
"errors"
"fmt"
"strconv"
"strings"
)
func main() {
t1 := "01:30"
seconds, _ := ConvertTimeFormat(t1) // not working fine for this
fmt.Println(seconds)
t2 := "01:01:15"
second, _ := ConvertTimeFormat(t2) // working fine for this
fmt.Println(second)
}
func ConvertTimeFormat(st string) (int, error) {
var sh, sm, ss string
parts := strings.Split(st, ":")
switch len(parts) {
case 2:
sm = parts[0]
ss = parts[1]
case 3:
sh = parts[0]
sm = parts[1]
ss = parts[2]
default:
return 0, errors.New("Invalid format")
}
var (
h, m, s int
err     error
)
if sh != "" {
h, err = strconv.Atoi(sh)
if err != nil {
return 0, err
}
}
m, err = strconv.Atoi(sm)
if err != nil {
return 0, err
}
s, err = strconv.Atoi(ss)
if err != nil {
return 0, err
}
return h*3600 + m*60 + s, nil
}

Go playground

Another solution is to handle the error and try to parse it in the another format:

func ConvertTimeFormat(st string) (int, error) {
var h, m, s int
_, err := fmt.Sscanf(st, "%d:%d:%d", &h, &m, &s)
fmt.Println(h, m, s, err)
if err != nil {
h, m, s = 0, 0, 0
_, err = fmt.Sscanf(st, "%d:%d", &m, &s)
if err != nil {
return 0, err
}
}
return h*3600 + m*60 + s, nil
}

Split input string at ":" and reverse iterate.
Multiply fields by 1, 60 or 3600 as per position
Add to seconds

Code

var mult = []int{1, 60, 60 * 60}
func ConvertTimeFormat(timeStr string) (int, error) {
var secs int
slice := strings.Split(timeStr, ":")
arrlen := len(slice)// Check length <=3 here
for i := arrlen - 1; i >= 0; i-- {
elem, err := strconv.Atoi(slice[i])
if err != nil {
return -1, fmt.Errorf("error parsing [%s] in [%s]  [%v]",
slice[i], timeStr, err)
}
secs += (elem * mult[arrlen-i-1])
}
return secs, nil
}

Erroneous strings "", ":", ":20", "str:30, "::" etc will be reported by Atoi()

Edit:

Could also use multiplier instead of array, would be extra multiplication operation.

func ConvertTimeFormat(timeStr string) (int, error) {
multiplier := 1
for i := arrlen - 1; i >= 0; i-- {
...	
secs += (elem * multiplier)
multiplier *= 60
}
return secs, nil
}

maybe it's more easier to understand and rewrite by yourself. using official package time .

    func main() {
t1 := "01:30"
backSeconds(t1)
t2 := "01:01:15"
backSeconds(t2)
// input:  01:30 ----deal:  01m30s ----result:  90
// input:  01:01:15 ----deal:  01h01m15s ----result:  3675
}
func backSeconds(str string) {
deal := preDeal(str)
parse, err := time.ParseDuration(deal)
if err != nil {
log.Println(err)
}
fmt.Println("input: ", str, "----deal: ", deal, "----result: ", parse.Seconds())
}
func preDeal(str string) string {
list := strings.Split(str, ":")
var build strings.Builder
tType := []string{"s", "m", "h"}
j := len(list) - 1
for i := 0; i < len(list); i++ {
build.WriteString(list[i] + tType[j-i])
}
return build.String()
}