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[go/en] Add value/reference semantics information for arr/slices.

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Petr Houška 2020-02-08 23:11:33 +01:00 committed by GitHub
parent e021d05c2f
commit cd631729a8
1 changed files with 10 additions and 0 deletions
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@ -109,6 +109,11 @@ can include line breaks.` // Same string type.
a5 := [...]int{3, 1, 5, 10, 100} // An array initialized with a fixed size of five a5 := [...]int{3, 1, 5, 10, 100} // An array initialized with a fixed size of five
// elements, with values 3, 1, 5, 10, and 100. // elements, with values 3, 1, 5, 10, and 100.
// Arrays have value semantics.
a4_cpy := a4 // a4_cpy is a copy of a4, two separate instances.
a4_cpy[0] = 25 // Only a4_cpy is changed, a4 stays the same.
fmt.Println(a4_cpy[0] == a4[0]) // false
// Slices have dynamic size. Arrays and slices each have advantages // Slices have dynamic size. Arrays and slices each have advantages
// but use cases for slices are much more common. // but use cases for slices are much more common.
s3 := []int{4, 5, 9} // Compare to a5. No ellipsis here. s3 := []int{4, 5, 9} // Compare to a5. No ellipsis here.
@ -116,6 +121,11 @@ can include line breaks.` // Same string type.
var d2 [][]float64 // Declaration only, nothing allocated here. var d2 [][]float64 // Declaration only, nothing allocated here.
bs := []byte("a slice") // Type conversion syntax. bs := []byte("a slice") // Type conversion syntax.
// Slices (as well as maps and channels) have reference semantics.
s3_cpy := s3 // Both variables point to the same instance.
s3_cpy[0] = 0 // Which means both are updated.
fmt.Println(s3_cpy[0] == s3[0]) // true
// Because they are dynamic, slices can be appended to on-demand. // Because they are dynamic, slices can be appended to on-demand.
// To append elements to a slice, the built-in append() function is used. // To append elements to a slice, the built-in append() function is used.
// First argument is a slice to which we are appending. Commonly, // First argument is a slice to which we are appending. Commonly,