Argument reuse
Golang’s fmt package provides many features for formatting and printing.
Here is a small example:
package main
import "fmt"
func main() {
s := "Hello"
fmt.Printf("%s\n", s) // Hello
}
Sometimes you need to use same object for displaying in different formats. Most people use this way:
package main
import "fmt"
func main() {
s := "Hello"
fmt.Printf("value: %s, type: %T\n", s, s) // value: Hello, type: string
}
As you see, we use s twice. We have another option: [INDEX] usage:
package main
import "fmt"
func main() {
s := "Hello"
fmt.Printf("value: %[1]s, type: %[1]T\n", s) // value: Hello, type: string
}
%[1]s means, use the first argument… Now, we are passing s to Printf
function only once. Here is a bit complex example:
package main
import "fmt"
func main() {
s := "Hello"
n := 1
fmt.Printf("value of s: %[1]s, type of s: %[1]T\nvalue of n: %[2]d, type of n: %[2]T\n", s, n)
// value of s: Hello, type of s: string
// value of n: 1, type of n: int
}
Happy coding!
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