68 lines
1.7 KiB
Go
68 lines
1.7 KiB
Go
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package main
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import (
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"fmt"
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"reflect"
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)
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type FavoriteNumbers struct {
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num1, num2, num3 int
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}
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func main() {
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fmt.Println("Map, maps keys to values")
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fmt.Println("Zero value of a map is nil")
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fmt.Println("make function return a map of the given type, initialized and ready for use")
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m := make(map[string]FavoriteNumbers)
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/* or:
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var m map[string]FavoriteNumbers // Even if you declared map with this line, you must use make to initialize map
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m = make(map[string]FavoriteNumbers)
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*/
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m["Aliberk"] = FavoriteNumbers{1, 2, 3}
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m["Deniz"] = FavoriteNumbers{4, 5, 6}
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fmt.Println(m["Aliberk"])
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var map2 map[int]int
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// map2[5] = 1 // Runtime error without make: "panic: assignment to entry in nil map"
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map2 = make(map[int]int)
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map2[1] = 3
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// map2["2"] = 1 // Compile error
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map2['3'] = 1 // not 3, 51 (ASCII value)
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fmt.Println(map2[5]) // any other non-declared value is zero
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fmt.Println(map2[1])
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fmt.Println(map2[3]) // 0
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fmt.Println(map2[51]) // 1
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fmt.Println(map2)
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fmt.Printf("\nYou can also use Map Literals for assigning values directly, but keys are required!\n")
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map3 := map[string]FavoriteNumbers{
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"Prime": FavoriteNumbers{2, 3, 5}, // FavoriteNumbers are not necessary in there
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"bigger": {123, 124, 125},
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}
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fmt.Println(map3)
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fmt.Println(reflect.TypeOf(map3).Kind())
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fmt.Println(reflect.TypeOf(map3["Prime"]).Kind())
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fmt.Println(reflect.TypeOf(map3["Prime"].num1).Kind())
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fmt.Printf("\n\n%p\n", map3)
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fmt.Printf("%p\n", &map3)
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fmt.Printf("\nElements can be deleted with delete function:\n")
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delete(map3, "bigger")
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fmt.Println(map3)
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fmt.Println("Also Elements can be tested like this:")
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elem, ok := map3["bigger"]
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fmt.Println(elem, ok)
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elem, ok = map3["Prime"]
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fmt.Println(elem, ok)
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}
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