make和new的区别

// 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

// 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

参照上面go源码中,make和new函数的签名上的注释,可以看到几个区别:

  • make返回的是对象,而new返回的是指向对象的一个指针
  • make只能使用在map、slice、channel三种类型,new可以作用在任意类型上
  • make会分配内存同时根据不同的类型进行适当的初始化,可以通过参数进行一定的控制,new只会分配内存并将对象设置为0值
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