How to design a progress bar logic when inputs are less than 10?

I am parsing strings from an array and showing progress as the strings are parsed. This is my logic but it doesn't scale for inputs less than 10.

Divide by zero is already taken care of during the initial part of the function for 100*i/(lineLen-1)

progress := 0
for i:= 0; i<lineLen;i++ {
 //.. lineLen = array length
//.....String processing...
if (100*i/(lineLen-1)) >= progress {
     fmt.Printf("--%d%s--", progress, "%")
     progress += 10
}
}

I understand that you need to floor all the percentages to a multiple of 10.

You could try something like the following.

lineLen := 4
progress := 0
for i := 0; i < lineLen; i++ {
	// Rounding down to the nearest multiple of 10.
	actualProgress := (100 * (i+1) / lineLen)
	if actualProgress >= progress {
		roundedProgress := (actualProgress / 10) * 10
		// Condition to make sure the previous progress percentage is not repeated.
		if roundedProgress != progress{
			progress = roundedProgress
			fmt.Printf("--%d%s--", progress, "%")
		}
	}
}

Link

Have a look at https://play.golang.org/p/xtRtk1T_ZW (code reproduced below):

func main() {
	// outputMax is the number of progress items to print, excluding the 100% completion item.
	// There will always be at least 2 items output: 0% and 100%.
	outputMax := 10

	for lineLen := 1; lineLen < 200; lineLen++ {
		fmt.Printf("lineLen=%-3d    ", lineLen)
		printProgress(lineLen, outputMax)
	}
}

// Calculate the current progress.
func progress(current, max int) int {
	return 100 * current / max
}

// Calculate the number of items in a group.
func groupItems(total, limit int) int {
	v := total / limit
	if total%limit != 0 {
		v++
	}
	return v
}

// Print the progress bar.
func printProgress(lineLen, outputMax int) {
	itemsPerGroup := groupItems(lineLen, outputMax)
	for i := 0; i < lineLen; i++ {
		if i%itemsPerGroup == 0 {
			fmt.Printf("--%d%%--", progress(i, lineLen))
		}
	}
	fmt.Println("--100%--")
}

If you want, you can execute a loop over various values of outputMax and lineLen using https://play.golang.org/p/aR6coeLhAk to see which value for outputMax you like (8 <= outputMax < 13 looks best to me). Output of the progress bar is disabled by default, but you can easily enable it in main.