Go 学习笔记

m := make(map[string]int)
m["Answer"] = 48
v, ok := m["Answer"]
fmt.Println("The value:", v, "Present?", ok)
delete(m, "Answer")
fmt.Println("The value:", v, "Present?", ok)

The value: 48 Present? true
The value: 0 Present? false

func main() {
    a := make([]int, 5)
    printSlice("a", a)
    b := make([]int, 0, 5)
    printSlice("b", b)
    c := b[:2]
    printSlice("c", c)
    d := c[2:5]
    printSlice("d", d)
    printSlice("b", b)
}
func printSlice(s string, x []int) {
    fmt.Printf("%s len=%d cap=%d %v\n",
        s, len(x), cap(x), x)
}

a len=5 cap=5 [0 0 0 0 0]
b len=0 cap=5 []
c len=2 cap=5 [0 0]
d len=3 cap=3 [0 0 0]
b len=0 cap=5 []

var pow = []string{"hehe", "haha"}
for i, v := range pow {
        fmt.Printf("2**%d = %s\n", i, v)
    }

2**0 = hehe
2**1 = haha