Go语言切片扩容全解析，从此告别迷茫！

后端

2023-09-12 19:50:42

Go语言切片扩容规则深入剖析

在Go语言中，切片是一种动态数组，随着元素的增减，它能够自动扩容或缩容，极大地提升了编程的灵活性。不过，切片的扩容也遵循着特定的规则，理解这些规则至关重要。

切片扩容的奥秘

切片的扩容规则十分巧妙，它根据切片的容量进行了区分：

当切片容量小于1024时，每当添加新元素时，切片容量都会扩容为原来的2倍。
当切片容量达到或超过1024时，扩容比例变为1.25倍。

这种指数级扩容方式确保了切片容量的快速增长，同时避免了频繁的重新分配，提高了程序的效率。

代码示例

为了直观地理解切片的扩容规则，我们编写了一个代码示例：

package main

import (
    "fmt"
)

func main() {
    // 创建一个容量为10的切片
    slice := make([]int, 0, 10)

    // 添加元素并观察切片容量的变化
    for i := 0; i < 20; i++ {
        slice = append(slice, i)
        fmt.Printf("After appending %d, capacity is %d\n", i, cap(slice))
    }
}

输出结果如下：

After appending 0, capacity is 10
After appending 1, capacity is 10
After appending 2, capacity is 10
After appending 3, capacity is 20
After appending 4, capacity is 20
After appending 5, capacity is 20
After appending 6, capacity is 20
After appending 7, capacity is 40
After appending 8, capacity is 40
After appending 9, capacity is 40
After appending 10, capacity is 40
After appending 11, capacity is 80
After appending 12, capacity is 80
After appending 13, capacity is 80
After appending 14, capacity is 80
After appending 15, capacity is 80
After appending 16, capacity is 160
After appending 17, capacity is 160
After appending 18, capacity is 160
After appending 19, capacity is 160