insertion and selectin sort in cpp

#include <iostream>
using namespace std;

void insertionsort(int *arr, int n) {
for(int i = 0; i < n; i++) {
int j = i;

while(j > 0 && arr[j-1] > arr[j]){
  int temp = arr[j-1];
  arr[j-1] = arr[j];
  arr[j] = temp;
  j--;
}

}
}

void selection_sort(int *arr,int length){
for(int i = 0; i < length-1; i++) {
int min = i;
for(int j = i+1; j < length; j++) {
if(arr[min] > arr[j])
min = j;
}

  if(min != i) {
    int temp = arr[min];
    arr[min] = arr[i];
    arr[i] = temp;
  }

}
}
int main()
{
int arr[] = {12,21,88,0};
int length = sizeof(arr) / sizeof(arr[0]);
selection_sort(arr,length);
for(int i = 0; i < length; i++) {
cout << arr[i] << " ";
}

return 0;

}