开始-分配多个变量时出错

Question

I am learner of go language. This is very basic question. Please check the below sample code, and look into 3rd line.

a := [3]int{10,20} 
var i int = 50
i, a[2] = 100, i

fmt.Println(i)   //100
fmt.Println(a)   //[10 20 50]

I have overwriten the value 100 in i variable and immediately applied the int array. When I printed the array, the new value was not printed. How does multiple variable assignment work in go? Why the i value is not updated into the array immediately?

Answer 1

The assigment section of the Go spec mentions:

The assignment proceeds in two phases.

• First, the operands of index expressions and pointer indirections (including implicit pointer indirections in selectors) on the left and the expressions on the right are all evaluated in the usual order.
• Second, the assignments are carried out in left-to-right order.

That means:

var i int = 50
i, a[2] = 100, i

• a[2] is assigned the i evaluated before assignment (50)
• i is assigned 100