Go 语言的切片

切片的声明

func TestSliceInit(t *testing.T) {
    var s0 []int
    t.Log(len(s0), cap(s0))
    
    s0 = append(s0, 1)
    t.Log(len(s0), cap(s0))
    
    s1 := []int{1, 2, 3, 4}
    t.Log(len(s1), cap(s1))
    
    s2 := make([]int, 3, 5)
    // 长度3，容量5
    t.Log(len(s2), cap(s2))
    // 只能访问前三个元素，不能访问s2[3]
    t.Log(s2[0], s2[1], s2[2])
    
    s2 = append(s2, 1)
    // 长度4，容量5
    t.Log(len(s2), cap(s2))
    // 能够访问前四个元素，不能访问s2[4]
    t.Log(s2[0], s2[1], s2[2], s2[3])
}

切片的容量增加

func TestSliceGrowing(t *testing.T) {
    s := []int{}
    for i := 0; i < 10; i++ {
        s = append(s, i)
        // 容量会翻倍增加
        t.Log(len(s), cap(s))
    }
}

切片共享内容

func TestSliceShareMemory(t *testing.T) {
    months := []string{"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sept", "Oct", "Nov", "Dec"}
    Q2 := months[3:6]
    //[...] 3 9
    t.Log(Q2, len(Q2), cap(Q2))
    
    summer := year[5:8]
    t.Log(summer, len(summer), cap(summer))
    
    summer[0] = "Unknow"
    t.Log(Q2)
    t.Log(months)
}

切片的比较

func TestSliceComparing(t *testing.T) {
    a := []int{1, 2, 3, 4}
    b := []int{1, 2, 3, 4}
    // 切片不能进行比较
    if a == b {
        t.Log("equal")
    }
}