Golang : Interpolating or substituting variables in string examples

For this quick tutorial, we will explore how to interpolate(substitute) actual data into variables inside a string. Will keep these examples as simple as possible and once you are comfortable, do explore the advanced example at https://www.socketloop.com/tutorials/golang-auto-generate-reply-email-with-text-template-package

Example 1:

 package main

 import (
 "fmt"
 )

 func main() {
 msg := "%s has %d messages."

 name := "Steve"
 num := 50

 result := fmt.Sprintf(msg, name, num)

 fmt.Println(result)
 }

Output:

Steve has 50 messages.

To substitute more variables ( higher than 3), it is recommended to use the text/template package.

Example 2:

 package main

 import (
 "fmt"
 "os"
 "text/template"
 )

 type Data struct {
 Name string // has to be uppercase/exportable/public
 Num  uint // for the interpolation/substitution to work
 }

 func main() {
 msg := "{{.Name}} has {{.Num}} messages.\n"

 substitute := Data{"Steve", 50}

 tmpl, err := template.New("msg").Parse(msg)

 err = tmpl.Execute(os.Stdout, substitute)

 if err != nil {
 fmt.Println(err)
 }
 }

Output:

Steve has 50 messages.

References:

https://www.socketloop.com/tutorials/golang-auto-generate-reply-email-with-text-template-package

https://golang.org/pkg/text/template/

https://www.socketloop.com/tutorials/golang-find-replace-character-in-string