GoLang Print the Number of Occurances of the Values in an Array

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

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
    dict:= make(map[int]int)
    for _ , num :=  range arr {
        dict[num] = dict[num]+1
    }
    fmt.Println(dict)
}

This prints map[67:1 90:1 10:2 20:2 30:1 56:1]

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.

You have a couple of problems here.

1. You are declaring dict as a map value, but it is not assigned any value and so is nil
2. You are not updating the count as you are expecting

To fix the issue with the map, use the make function to assign an empty map to the dict variable. As explained above.

You are expecting:

map[10:2 20:2 30:1 56:1 67:1 90:1]

But even if the map was initialised correctly, you would get:

map[10:1 20:1 30:1 56:1 67:1 90:1]

Don't use a counter outside of the map itself. Use the existing value.

According to the Go tour maps return a zero value when queried with a non-existing key. This is a nice feature for this task, see the below code

package main

import "fmt"

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

func printUniqueValue(arr []int) {
    dict := make(map[int]int)
    for _ , num :=  range arr {
        // dict[num] will return 0 if it hasn't yet been initialised
        dict[num] = dict[num] + 1
    }
    fmt.Println(dict)
}