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In Go, you can create an empty map using the `make` function. You need to specify what type of keys and values the map will hold.
myMap := make(map[string]int) // Creates an empty map with string keys and int values
You can also initialize a map with some key-value pairs right when you create it.
myMap := map[string]int{
"a": 1,
"b": 2,
"c": 3,
} // Creates a map with initial values
To get a value from a map, use its key. You can also check if a key exists and get a boolean result.
value, exists := myMap["b"] // Retrieves value for key "b" and checks if it exists
You can add new key-value pairs to a map by specifying the key and the value.
myMap["d"] = 4 // Adds a new key-value pair to the map
Update an existing value by assigning a new value to its key.
myMap["a"] = 10 // Updates the value for key "a" to 10
To remove a key-value pair from a map, use the `delete` function with the map and the key you want to remove.
delete(myMap, "c") // Removes the key-value pair with key "c"
A map in Go is a collection of key-value pairs where each key is unique. It's used to quickly find data using a key.
myMap := map[string]string{
"name": "Alice",
"city": "Wonderland",
} // Example map with string keys and values
A struct is a way to group related variables together. Each variable in a struct is called a field.
type Person struct{
Name string
Age int
} // Defines a struct with a name and age
Define a struct by naming it and listing its fields and their types.
type Car struct{
Brand string
Year int
} // Defines a Car struct with brand and year fields
Create an instance of a struct by using its name and providing values for its fields.
myCar := Car{Brand: "Toyota", Year: 2022} // Creates a Car instance
You can add functions to structs, which operate on the struct’s fields. These functions are called methods.
func (p Person) Greet() string {
return "Hello, " + p.Name
} // Method to greet using a Person struct
Access fields in a struct using the dot `.` operator.
fmt.Println(myCar.Brand) // Prints the brand of the car
To modify a struct’s fields in a function, pass the struct as a pointer. This way, changes affect the original struct.
func (p *Person) HaveBirthday() {
p.Age++
}
p1 := Person{Name: "Bob", Age: 30}
p1.HaveBirthday() // p1.Age is now 31
You can access fields of a struct pointer without explicitly dereferencing it, using the dot `.` syntax.
pointerToCar := &myCar
fmt.Println(pointerToCar.Year) // Prints the year of the car
You can use arrays to store multiple instances of the same struct type.
people := []Person{
{Name: "Alice", Age: 30},
{Name: "Bob", Age: 25},
} // Array of Person structs
A struct can contain other structs as fields, allowing for more complex data structures.
type Address struct {
Street string
City string
}
type Person struct {
Name string
Address Address
} // Struct with a nested Address struct
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