golang - Why ++ and — not work in expressions?

Question

What we take for granted in other languages and almost expect it to work in go, won\'t work - its almost so natural to do this, so why isn\'t the compiler happy? Just feeling li

Answer 1

Specifically, ++ and -- are statements because it can be very difficult to understand the order of evaluation when they're in an expression.

Consider the following:

// This is not valid Go!
x := 1
x = x++ + x
y := 1
y = ++y + y

What would you expect x to be? What would you expect y to be? By contrast, the order of evaluation is very clear when this is a statement.

Answer 2

Just to help clarify, an expression has a =, := or += in them. A statement (such as ++ and —) does not. See https://stackoverflow.com/a/1720029/12817546.

package main

import "fmt"

var x int

func f(x int) {
    x = x + 1      //expression
    x++            //statement
    fmt.Println(x) //2
}

func main() {
    f(x) //expression statement
}

An "expression" specifies the computation of a value by applying operators and functions to operands. See https://golang.org/ref/spec#Expressions.

A "statement" controls execution. See https://golang.org/ref/spec#Statements.

An "expression statement" is a function and method call or receive operation that appears in a statement. See https://golang.org/ref/spec#Expression_statements.

Answer 3

++ and -- are statements in golang, not expressions