Difference between new() and make() in Golang

go new() vs make()

Golang is a statically-typed language with a garbage collector that makes it easy to write concurrent programs. In Golang, there are two ways to allocate memory: make and new. While both of these keywords can be used to allocate memory, they are used for different purposes.

new

The new keyword in Golang is used to create a new instance of a variable, and it returns a pointer to the memory allocated. It is used for allocating memory for the value of a certain type. new takes a type as its argument and returns a pointer to a newly allocated zero value of that type.

example of new:

// creating a new pointer to an int variable
var x *int = new(int)

// setting the value of the newly allocated int variable
*x = 5

// output: 5
fmt.Println(*x)

In the above example, new is used to allocate memory for an int variable, and the pointer to this newly allocated memory is stored in the x variable. The value of the int variable is then set to 5.

make

The make keyword in Golang is used to create slices, maps, and channels, and it returns a value of the type that was created. Unlike new, make returns a value of the type being created, not a pointer to the type.

example of make :

// creating a new slice with a length of 3
var s []int = make([]int, 3)

// setting the values of the slice
s[0] = 1
s[1] = 2
s[2] = 3

// output: [1 2 3]
fmt.Println(s)

In the above example, make is used to create a new slice of int type with a length of 3, and the slice is stored in the s variable. The values of the slice are then set to 1, 2, and 3.

Keypoints

1. new returns a pointer to the memory allocated, while make returns the value of the type being created.
2. new only works with basic types such as int, float, bool, etc. make is used for creating slices, maps, and channels.
3. new allocates zeroed memory, while make allocates memory and initializes it.

Conclusion

In Golang, new and make are two keywords that are used for allocating memory. new is used for creating a new instance of a variable, and it returns a pointer to the memory allocated. make is used for creating slices, maps, and channels, and it returns the value of the type being created. Knowing the differences between these two keywords is important when writing Golang code.

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