比较 是否相等 comparable

小结：

1、结构体、指针是否相等

https://go.dev/ref/spec#Comparison_operators

 

Comparison operators

Comparison operators compare two operands and yield an untyped boolean value.

==    equal
!=    not equal
<     less
<=    less or equal
>     greater
>=    greater or equal

In any comparison, the first operand must be assignable to the type of the second operand, or vice versa.

The equality operators == and != apply to operands that are comparable. The ordering operators <, <=, >, and >= apply to operands that are ordered. These terms and the result of the comparisons are defined as follows:

• Boolean values are comparable. Two boolean values are equal if they are either both true or both false.
• Integer values are comparable and ordered, in the usual way.
• Floating-point values are comparable and ordered, as defined by the IEEE-754 standard.
• Complex values are comparable. Two complex values u and v are equal if both real(u) == real(v) and imag(u) == imag(v).
• String values are comparable and ordered, lexically byte-wise.
• Pointer values are comparable. Two pointer values are equal if they point to the same variable or if both have value nil. Pointers to distinct zero-size variables may or may not be equal.
• Channel values are comparable. Two channel values are equal if they were created by the same call to make or if both have value nil.
• Interface values are comparable. Two interface values are equal if they have identical dynamic types and equal dynamic values or if both have value nil.
• A value x of non-interface type X and a value t of interface type T are comparable when values of type X are comparable and X implements T. They are equal if t's dynamic type is identical to X and t's dynamic value is equal to x.
• Struct values are comparable if all their fields are comparable. Two struct values are equal if their corresponding non-blank fields are equal.
• Array values are comparable if values of the array element type are comparable. Two array values are equal if their corresponding elements are equal.

A comparison of two interface values with identical dynamic types causes a run-time panic if values of that type are not comparable. This behavior applies not only to direct interface value comparisons but also when comparing arrays of interface values or structs with interface-valued fields.

Slice, map, and function values are not comparable. However, as a special case, a slice, map, or function value may be compared to the predeclared identifier nil. Comparison of pointer, channel, and interface values to nil is also allowed and follows from the general rules above.

const c = 3 < 4            // c is the untyped boolean constant true

type MyBool bool
var x, y int
var (
	// The result of a comparison is an untyped boolean.
	// The usual assignment rules apply.
	b3        = x == y // b3 has type bool
	b4 bool   = x == y // b4 has type bool
	b5 MyBool = x == y // b5 has type MyBool
)