Golang: Print

Print

To print, load the the package fmt, then use the function fmt.Printf.

Example:

fmt.Printf("there are %v apples\n", 3)

• The first argument is a string. The string can contain many special placeholder characters (called verbs) that start with the percent character %.
• Second argument and rest arguments are used to fill the placeholders.

package main

import "fmt"

func main() {

	var x = "John"
	var y = 36

	fmt.Printf("name is %v, age is %v\n", x, y)
	// name is John, age is 36

}

Printf Verbs (placeholders)

Printf Verbs converts a value to a string, in a specific format. e.g. convert a integer to string type, or int to string type but in hexadecimal form, or convert a array into a string format.

Here's the most useful verbs:

%v

Any value. Convert to a format that's human readable.

%#v

Convert it to golang syntax that represents the value.

%+v

If value is struct, also show the field names.

%T

Type of the value

%%

A literal percent sign

Complete List of Verbs

• Golang: Printf Verbs

Print Line

For quick printing, use

fmt.Println(v1, v2, etc)

it's similar to fmt.Printf with "%v" for format.

package main

import "fmt"

func main() {

	var x = 3
	var y = 4
	fmt.Println(x, y) // 3 4
}

Example: Print Type

It is very useful to print the type of a value, when learning go.

fmt.Printf("%T\n", val)

package main

import "fmt"

// using Printf to show different types of value

func main() {

	var x = 3
	fmt.Printf("%v\n", x) // 3
	fmt.Printf("%T\n", x) // int

	var x2 = 3.4
	fmt.Printf("%v\n", x2) // 3.4
	fmt.Printf("%T\n", x2) // float64

}