在struct golang中打印一个struct

Question

I want to print a certain item within a struct, that is within a struct. Example:
Pretend I have made up a blueprint struct, and are making an new one
Pretend I have a myshapes struct, that contains a title, # of circles, and squares

car := blueprints{
dots: 5,
lines: 25,
shapes: []myshapes{
    myshapes{
        title:"car #1",
        circles:5,
        squares:7,
    },
    myshapes{
        title:"car #2",
        circles:2,
        squares:14,
    },
}

How do I print:

title:"car #1"
circles:5
squares:7
title:"car #2"
circles:2
squares:14

Answer 1

The example below shows how you'd print a particular field value of a struct:

type child struct {
    name string
    age int
}

type parent struct {
    name string
    age int
    children child
}

func main() {
    family := parent{
        name: "John",
        age: 40,
        children: child{
            name: "Johnny",
            age: 10,
        },
    }

    fmt.Println(family.children.name); // Prints "Johnny"
}

The code above would print "Johnny", which is a value of a struct within the parent struct. The code doesn't make much sense, however, because the field is children, yet there is only ever able to be one child as its value.

Let's leverage slices. Now that we know how to print a particular value, all we would need for your case is to loop over a slice and print the same way we did above.

We can do that like this:

type child struct {
    name string
    age int
}

type parent struct {
    name string
    age int
    children []child
}

func main() {
    family := parent{
        name: "John",
        age: 40,
        children: []child{
            child{
                name: "Johnny",
                age: 10,
            },
            child{
                name: "Jenna",
                age: 7,
            },
        },
    }

    for _, child := range family.children {
        fmt.Println(child.name);
    }
}

The above example will pront "Johnny" and "Jenna".

You can use a similar pattern to what I showed above in your own code to loop through your structs and print whatever value your heart desires :)

---

Keep in mind, there are many ways to loop through things. For example, all the following loops would print "Johnny" and "Jenna" from the examples above.

for _, child:= range family.children{ // Prints "Jonny" and "Jenna"
    fmt.Println(child.name); 
}

for i, _ := range family.children{ // Prints "Jonny" and "Jenna"
    fmt.Println(family.children[i].name);
}

for i := 0; i < len(family.children); i++ { // Prints "Jonny" and "Jenna"
    fmt.Println(family.children[i].name);
}