diff options
Diffstat (limited to 'go.html.markdown')
| -rw-r--r-- | go.html.markdown | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/go.html.markdown b/go.html.markdown index 49f1ade4..739ec05d 100644 --- a/go.html.markdown +++ b/go.html.markdown @@ -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 // 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 // but use cases for slices are much more common. 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. 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. // To append elements to a slice, the built-in append() function is used. // First argument is a slice to which we are appending. Commonly, @@ -168,10 +178,11 @@ func learnNamedReturns(x, y int) (z int) { // Go is fully garbage collected. It has pointers but no pointer arithmetic. // You can make a mistake with a nil pointer, but not by incrementing a pointer. +// Unlike in C/Cpp taking and returning an address of a local varible is also safe. func learnMemory() (p, q *int) { // Named return values p and q have type pointer to int. p = new(int) // Built-in function new allocates memory. - // The allocated int is initialized to 0, p is no longer nil. + // The allocated int slice is initialized to 0, p is no longer nil. s := make([]int, 20) // Allocate 20 ints as a single block of memory. s[3] = 7 // Assign one of them. r := -2 // Declare another local variable. |