New和Make的区别
以下是Go1.19中对new()和make()函数的解释：
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// The new built-in function allocates memory. The first argument is a type,
// not a value, and the value returned is a pointer to a newly
// allocated zero value of that type.
func new(Type) *Type
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new()是一个新的分配内存的函数，第一个参数是类型，不是值，返回的值是指向该类型零值的指针。
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// The make built-in function allocates and initializes an object of type
// slice, map, or chan (only). Like new, the first argument is a type, not a
// value. Unlike new, make's return type is the same as the type of its
// argument, not a pointer to it. The specification of the result depends on
// the type:
//
// Slice: The size specifies the length. The capacity of the slice is
// equal to its length. A second integer argument may be provided to
// specify a different capacity; it must be no smaller than the
// length. For example, make([]int, 0, 10) allocates an underlying array
// of size 10 and returns a slice of length 0 and capacity 10 that is
// backed by this underlying array.
// Map: An empty map is allocated with enough space to hold the
// specified number of elements. The size may be omitted, in which case
// a small starting size is allocated.
// Channel: The channel's buffer is initialized with the specified
// buffer capacity. If zero, or the size is omitted, the channel is
// unbuffered.
func make(t Type, size ...IntegerType) Type
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make()函数用于初始化slice,map和channel。和new()比较像的是第一个参数也是一个类型，不是值。区别于new的地方在于make()返回的值和他参数类型是一样的。第二个类型size是一个可变长类型的参数，作用如下:
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m := make(map[int]string, 5)
s := make([]int, 5, 10)
channel := make(chan string, 5)
fmt.Println(m, s, channel)
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初始化一个slice,传入第一个参数为类型，第二个参数为长度，第三个参数为容量，容量不可以小于长度。初始化map的可变参数只有容量cap,而初始化channel的可变参数为缓冲大小。