go-slice-append

slice append

tags: learning go programming

content

Note

append might create a new array (a new underlying array of the slice).
that’s why when calling append, we need to assign it back to the original function
(mySlice = append(mySlice, 1))

• when appending to an underlying slice that has reached max capacity, Go creates a new backing array
• when appending to an underlying slice that has NOT reached max capacity, Go uses existing array

func main() {
	a := make([]int, 3, 3)
	b := make([]int, 3, 10)
	c := append(a, 4)
	d := append(a, 5)
	fmt.Println("c is: ", c, ", addr of c is: ", &c[0])
	fmt.Println("d is: ", d, ", addr of d is: ", &d[0])
 
	e := append(b, 4)
	f := append(b, 5)
	fmt.Println("e is: ", e, ", addr of e is: ", &e[0])
	fmt.Println("f is: ", f, ", addr of f is: ", &f[0])
}

this code gives the fellowing output

c is:  [0 0 0 4] , addr of c is:  0x1400012a030
d is:  [0 0 0 5] , addr of d is:  0x1400012a060
// c and d has different addresses
 
e is:  [0 0 0 5] , addr of e is:  0x1400012e000
f is:  [0 0 0 5] , addr of f is:  0x1400012e000
// e and f has the same addresses

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go-slice-and-array go-slice-and-array-memory

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