golang append() evaluated but not used

问题:

func main(){      var array [10]int      sliceA := array[0:5]      append(sliceA, 4)      fmt.Println(sliceA) } 

Error : append(sliceA, 4) evaluated but not used

I don't Know why? The slice append operation is not run...

回答1:

Refer: Appending to and copying slices

In Go, arguments are passed by value.

Typical append usage is:

a = append(a, x) 

You need to write:

func main(){     var array [10]int     sliceA := array[0:5]     // append(sliceA, 4)  // discard     sliceA = append(sliceA, 4)  // keep     fmt.Println(sliceA) } 

Output:

[0 0 0 0 0 4] 

I hope it helps.

回答2:

sliceA =append(sliceA, 4) append returns a slice containing one or more new values. Note that we need to accept a return value from append as we may get a new slice value.

回答3:

you may try this:

sliceA = append(sliceA, 4) 

built-in function append([]type, ...type) returns an array/slice of type, which should be assigned to the value you wanted, while the input array/slice is just a source. Simply, outputSlice = append(sourceSlice, appendedValue)

回答4:

Per the Go docs:

The resulting value of append is a slice containing all the elements of the original slice plus the provided values.

So the return value of 'append', will contain your original slice with the appended portion.

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