GoLang打印数组中值的出现次数

Question

The following is my code where I need to Print the number of occurances of each values in an array.

package main

import "fmt"

func main(){
    //Initialize an array 
    inputArray := []int{10,20,30,56,67,90,10,20}
    printUniqueValue(inputArray)
}

func printUniqueValue( arr []int){
    //Create a   dictionary of values for each element
    var  dict map[int]int 
    count := 0
    for _ , num :=  range arr {
        dict[num] = count+1
    }
    fmt.Println(dict)
}

But I couldn't construct the dictionary as I wish like , dict[10] should have value 2. Sample Expected Output :

dict[10] = 2
dict[20] = 2
dict[30] = 1  

Error I got: panic: assignment to entry in nil map

Answer 1

You need to initialize dict with a non-nil map; one way would be with var dict = make(map[int]int).

Once you fix that, you will also need to deal with the logic error in dict[num] = count+1, where the count of that value is set to 1 (count is always 0) instead of one more than the previous value.