Golang : Print leading(padding) zero or spaces in fmt.Printf?

Problem :

You want to include leading zero or spaces in front(prefix) of integer when printing out with fmt.Println() or fmt.Printf() functions. How to do that?

Solution :

From https://golang.org/pkg/fmt/ - Other flags:

+ always print a sign for numeric values; guarantee ASCII-only output for %q (%+q)

- pad with spaces on the right rather than the left (left-justify the field)

# alternate format: add leading 0 for octal (%#o), 0x for hex (%#x);0X for hex (%#X); suppress 0x for %p (%#p); for %q, print a raw (backquoted) string if strconv.CanBackquote returns true; write e.g. U+0078 'x' if the character is printable for %U (%#U).

' ' (space) leave a space for elided sign in numbers (% d); put spaces between bytes printing strings or slices in hex (% x, % X)

0 pad with leading zeros rather than spaces; for numbers, this moves the padding after the sign

Code example :

 package main

 import "fmt"

 func main() {
  // you want to display 000108 (length = 6)
  // pad zero to total length of 6
  // d
  fmt.Printf("Leading or padded with zero :  |%06d|\n", 108)

  // pad spaces in front(prefix)
  fmt.Printf("Leading or padded with space : |%6d|\n", 108)

 }

Output :

Leading or padded with zero : |000108|

Leading or padded with space : | 108|

References :

https://golang.org/pkg/fmt/

http://stackoverflow.com/questions/153890/printing-leading-0s-in-c