Left padding means adding padding characters in start of string to make string to meet certain length. For example if number is two digits and we want to make it 10 digit number of visual display purpose, eight leading 0's can be padded to make the length of 10.

Go lang does not provide built-in function to meet padding, however padding can be met with simple concatenation.

Example : How to make left padding in Go lang

package main

import (
    "fmt"
    "strings"
)

func main() {

    maxInt := func(num1 int, num2 int) int {
        if num1 > num2 {
            return num1
        }
        return num2
    }

    inputData := "12"
    paddingCharacter := "0"
    paddingLength := 10

    stringLength := len(inputData)
    paddingData := strings.Repeat(paddingCharacter, maxInt(paddingLength-stringLength, 0))
    paddedData := paddingData + inputData
    fmt.Printf("Left padded number : %s\n", paddedData)
}

Output
Left padded number : 0000000012