Make slices, maps and channels

yourbasic.org/golang

Slices, maps and channels can be created with the built-in make function. The memory is initialized with zero values.

Call Type Description
make(T, n) slice slice of type T with length n
make(T, n, c) capacity c
make(T) map map of type T
make(T, n) initial room for approximately n elements
make(T) channel unbuffered channel of type T
make(T, n) buffered channel with buffer size n 
s := make([]int, 10, 100)      // slice with len(s) == 10, cap(s) == 100
m := make(map[string]int, 100) // map with initial room for ~100 elements
c := make(chan int, 10)        // channel with a buffer size of 10

Slices, arrays and maps can also be created with composite literals.

s := []string{"f", "o", "o"} // slice with len(s) == 3, cap(s) == 3
a := [...]int{1, 2}          // array with len(a) == 2
m := map[string]float64{     // map with two key-value elements
	"e":  2.71828,
	"pi": 3.1416,
}