一文带你揭秘Go中new()和make()函数的区别和用途

func new(Type) *Type

package main
import "fmt"
type Person struct {
    Name string
    Age  int
}
func main() {
    // Using new() to allocate memory for a Person struct
    p := new(Person)
    fmt.Printf("%T\n", p)
    // Accessing struct fields using the pointer
    p.Name = "Alice"
    p.Age = 30
    // Displaying the values
    fmt.Println("Name:", p.Name)
    fmt.Println("Age:", p.Age)
}

> go run main.go
*main.Person
Name: Alice
Age: 30

func make([]Type, len, cap) []Type

package main
import "fmt"
func main() {
    // Using make() to create a slice of integers
    numbers := make([]int, 5, 10)
    // Displaying the slice's length, capacity, and values
    fmt.Println("Length:", len(numbers))
    fmt.Println("Capacity:", cap(numbers))
    fmt.Println("Values:", numbers)
    // Using make() to create a slice of integers
    numbersWithoutOptional := make([]int, 5)
    // Displaying the slice's length, capacity, and values
    fmt.Println("Length:", len(numbersWithoutOptional))
    fmt.Println("Capacity:", cap(numbersWithoutOptional))
    fmt.Println("Values:", numbersWithoutOptional)
}

> go run main.go
Length: 5
Capacity: 10
Values: [0 0 0 0 0]
Length: 5
Capacity: 5
Values: [0 0 0 0 0]

func make(map[KeyType]ValueType, initialCapacity int) map[KeyType]ValueType

package main
import "fmt"
func main() {
    // Using make() to create a map of string keys and int values
    scores := make(map[string]int)
    // Adding values to the map
    scores["Alice"] = 95
    scores["Bob"] = 87
    // Displaying the map
    fmt.Println("Scores:", scores)
}
> go run main.go
Scores: map[Alice:95 Bob:87]

func make(chan Type, capacity int) chan Type

package main
import (
    "fmt"
    "time"
)
func main() {
    // Using make() to create an unbuffered channel of integers
    ch := make(chan int)
    // Sending data into the channel using a goroutine
    go func() {
        for i := 1; i <= 5; i++ {
            ch <- i
            time.Sleep(time.Second) // Simulating some work before sending the next value
        }
        close(ch)
    }()
    // Receiving data from the channel
    for num := range ch {
        fmt.Println("Received:", num)
    }
}
> go run main.go
Received: 1
Received: 2
Received: 3
Received: 4
Received: 5