12. make() and new()

Both methods are built-in and used for memory allocation and initialization of types.

new()

• Allocates zeroed storage for a variable of the specified type (“zeroed memory” refers to a block of memory that has all of its bits set to zero)
• Initializes it to the zero value of the type, e.g. 0 or an empty string.
• Returns a pointer to the newly allocated value
• new()can be used for all types of data, even simple types like integers
• Can be used with the varkeyword and short assignment :=
• Usually used for types like structs

max := new(Person)
 
fmt.Println(max)

In the example above, this will print a pointer to the empty struct: &{ 0}.

Values

new()can be used with both the varkeyword and the shortcut for variable initialization:

var people = new(map[string]Person)  
  
// or:   
  
people := new(map[string]Person)

make()

Compared to new()it can be only used for Go’s built-in types slices, maps and channels. make()does not only allocate memory, but also initialize the underlying data structure:

• For slices, make allocates an array of the specified type and size, and returns a slice reference to this array. This reference includes the length and capacity of the slice.
• For maps, make initializes the hash map structure.
• For channels, make sets up the channel’s data buffer and control structures.

make()can also be used with both the varkeyword and the short assignment :=.

var people = new(map[string]Person)  
  
// or:   
  
people := new(map[string]Person)

Next chapter: Packages and Package Management