Go: What is the difference between make and new?

make(T, ...) — initializes slices, maps, channels. new(T) — allocates zeroed memory, returns *T.

For slices, make([]int, 0, 50) preallocates capacity. For maps/channels, it creates internal structures. Result is ready to use.

1s := make([]int, 0, 50)  // preallocated
2m := make(map[string]int) // ready
3ch := make(chan int, 10)  // buffered

new returns pointer to zeroed memory. For slices/maps/channels, zero value is nil.

1p := new(int)    // *int → 0
2s := new([]int)  // *[]int → nil

When to use:

• make — always for slices, maps, channels.
• new — rarely.

Common mistakes:

• new([]int) → nil.
• make([]int, 10) → len=10.
• Not using capacity hint.
• make on wrong type.