print readable variables with golang

Question

How to print a map, struct or whatever in a readable way?

With PHP you can to this

echo \'
\';
print_r($var);
echo \'
\';
         


        

Answer 1

I think in many cases, using "%v" is concise enough:

fmt.Printf("%v", myVar)

From the fmt package's documentation page:

%v the value in a default format. when printing structs, the plus flag (%+v) adds field names

%#v a Go-syntax representation of the value

Here is an example:

package main

import "fmt"

func main() {
    // Define a struct, slice and map
    type Employee struct {
        id   int
        name string
        age  int
    }
    var eSlice []Employee
    var eMap map[int]Employee

    e1 := Employee{1, "Alex", 20}
    e2 := Employee{2, "Jack", 30}
    fmt.Printf("%v\n", e1)
    // output: {1 Alex 20}
    fmt.Printf("%+v\n", e1)
    // output: {id:1 name:Alex age:20}
    fmt.Printf("%#v\n", e1)
    // output: main.Employee{id:1, name:"Alex", age:20}

    eSlice = append(eSlice, e1, e2)
    fmt.Printf("%v\n", eSlice)
    // output: [{1 Alex 20} {2 Jack 30}]
    fmt.Printf("%#v\n", eSlice)
    // output: []main.Employee{main.Employee{id:1, name:"Alex", age:20}, main.Employee{id:2, name:"Jack", age:30}}

    eMap = make(map[int]Employee)
    eMap[1] = e1
    eMap[2] = e2
    fmt.Printf("%v\n", eMap)
    // output: map[1:{1 Alex 20} 2:{2 Jack 30}]
    fmt.Printf("%#v\n", eMap)
    // output: map[int]main.Employee{1:main.Employee{id:1, name:"Alex", age:20}, 2:main.Employee{id:2, name:"Jack", age:30}}
}