Go Memory Allocation: What's the Difference Between `new()` and `&`?

Distinguishing "new()" and "Regular" Allocation in Go

In Go, there are two methods for allocating memory: using the "new()" function or performing a "regular" allocation via the ampersand operator "&". While the two approaches may seem similar, they generate distinct results.

Understanding "new()"

The "new()" function allocates a new uninitialized value of the specified type and returns a pointer to that value. When "new()" is called, memory is allocated on the heap using "malloc". Unlike "regular" allocation, "new()" initializes the memory to the zero value for the specified type.

Understanding Regular Allocation via "&"

"Regular" allocation uses the "&" operator to obtain a pointer to an existing value. This method allocates memory on the stack and sets the returned pointer to the address of the allocated memory. "Regular" allocation does not initialize the memory, leaving it with uninitialized values.

Differences in Practice

The main difference between "new()" and "regular" allocation lies in the initialization of the allocated memory. "new()" initializes the memory to zero values, ensuring that the data is always predictable. In contrast, "regular" allocation leaves the memory uninitialized, requiring explicit initialization before use.

Usage Considerations

The choice between "new()" and "regular" allocation depends on the specific use case. "new()" is preferred when dealing with structs or complex data structures that require a predictable initial state. "Regular" allocation can be more efficient for simple data types like integers or floats that can be initialized directly.

Example

The following example illustrates the difference between "new()" and regular allocation:

package main

import "fmt"
import "reflect"

type Vector struct {
    x int
    y int
}

func main() {
    v := &Vector{}
    x := new(Vector)
    fmt.Println(reflect.TypeOf(v))
    fmt.Println(reflect.TypeOf(x))
}

Output:

*main.Vector
*main.Vector

As shown, both "new()" and "&" return a pointer to a Vector object. However, "new()" has initialized the values of the Vector to zero, while the "&" allocation has not.

The above is the detailed content of Go Memory Allocation: What's the Difference Between `new()` and `&`?. For more information, please follow other related articles on the PHP Chinese website!