array

Intro for ... range clause can be used to iterate 5 types of variables: array, slice, string, map and channel, and the following sheet gives a summary of the items of for ... range loops: Type 1st Item 2nd Item Array index value Slice index value String index (rune) value (rune) Map key value Channel value Example - Iterating on slice package main import "fmt" func main() { s := [] {1,2,3} for i,v := range s { fmt. [Read More]

Syntax In Go, the length is also a part of array type. So the following code declares an array: var array [3]int while “var slice []int” defines a slice. Arrays cannot be resized. Another way is to set the array entries as you declare the array: func main() { a := [2]string{"hello", "world!"} fmt.Printf("%q", a) } You can also use an implicit length when passing values to array using [...]: [Read More]

Golang prides itself on being a simple , pragmatic language and tried to avoid sugar that its creators feel are unnecessary. So lets add some map reduce functions ourselves to see what is involved: package main import "fmt" type MyList []string // a custom type can be a builtin type if you want it to be func (ml MyList) Filter(f func(string) bool) []string { na := []string{} for _, v := range ml { if add := f(v); add { na = append(na, v) } } return na } func (ml MyList) Reduce(f func(prev, current string, index int) string) []string { na := []string{} for i, v := range ml { if i == 0 { na = append(na, f("", v, i)) } else { na = append(na, f(ml[i-1], v, i)) } } return na } func (ml MyList) Map(f func(val string) *string) []string { na := []string{} for _, v := range ml { mVal := f(v) if nil ! [Read More]

In Go, array is a fixed length of continuous memory with specified type, while slice is just a reference which points to an underlying array. Since they are different types, they can’t assign value each other directly. See the following example: package main import "fmt" func main() { s := []int{1, 2, 3} var a [3]int fmt.Println(copy(a, s)) } Because copy only accepts slice argument, we can use the [:] to create a slice from array. [Read More]

When appending data into slice, if the underlying array of the slice doesn’t have enough space, a new array will be allocated. Then the elements in old array will be copied into this new memory, accompanied with adding new data behind. So when using Go built-in append function, you must always keep the idea that “the array may have been changed” in mind, and be very careful about it, otherwise, it may bite you! [Read More]