Product struct

Define a struct representing a product.

Project: a shopping cart

In this project you will build a small program that adds products, computes the total and prints the cart neatly. The first step is modeling the data: each product has a name, a unit price and a quantity.

type Urun struct {
    Ad    string
    Fiyat float64
    Adet  int
}

kalem := Urun{Ad: "Kalem", Fiyat: 12.5, Adet: 3}
fmt.Println(kalem.Ad, kalem.Fiyat*float64(kalem.Adet))  // Kalem 37.5

A struct gathers related fields into a single value; the cart will be a slice of these values.

A subtotal method

Adding a method that computes the product's subtotal keeps the calculation in one place:

func (u Urun) AraToplam() float64 {
    return u.Fiyat * float64(u.Adet)
}

Because Adet is an int, it is converted to float64 before multiplying; Go doesn't mix different number types on its own.

Exercise Product model

Write the Urun struct and the AraToplam() method. Print the subtotal for Urun{Ad: "Kalem", Fiyat: 12.5, Adet: 3}.

Show example solution

package main

import "fmt"

type Urun struct {
    Ad    string
    Fiyat float64
    Adet  int
}

func (u Urun) AraToplam() float64 {
    return u.Fiyat * float64(u.Adet)
}

func main() {
    k := Urun{Ad: "Kalem", Fiyat: 12.5, Adet: 3}
    fmt.Println(k.AraToplam())
}

Test yourself

What is the advantage of naming fields (<code>Urun{Ad: ..., Fiyat: ...}</code>)?
- The code stays correct even if the order changes or fields are added
- It runs faster
- It is required
- It uses less memory
Show answer

The code stays correct even if the order changes or fields are added — The unnamed form (Urun{"Kalem", 12.5, 3}) depends on field order; with named fields, omitted fields get their zero value.

Field access

u := Urun{Ad: "Defter", Fiyat: 20, Adet: 2}
fmt.Println(u____Ad)

Show answer

u := Urun{Ad: "Defter", Fiyat: 20, Adet: 2}
fmt.Println(u.Ad)

Field and type

Ad

string
Fiyat

float64
Adet

int
AraToplam()

Returns float64

Next lesson: Adding to cart

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