What is wrong in my C++ code

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C++

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C#3.5

C++98

C#6.0

There is compilation error in my code
_array bound is not an integer constant before']' token
_ARRAY bound is not an integer constant before ']' token

What I have tried:

#include<iostream>
using namespace std;

int n;

int _array[n];
int _ARRAY[n-1];
swap(int *i,int *k)
{int j;// js any temperory element
    j=*i;
    *i=*k;
    *k=j;
}
void sort(int _array[],int n )
{int hole;
    int i;
    hole = i;
    for(int hole=1;hole<n;hole++)>
    {
        if( hole>0 && _array[hole-1]>_array[hole])
        {swap(_array[hole],_array[hole-1]);
            hole=hole-1;
        }
}
}
int Findmindifference(){
int _array[n];
int _ARRAY[n-1];
 sort(_array,n);
for(int i=0;i<n-1;i++)>
{
    _ARRAY[i]=_array[i+1]-_array[i];
}
    sort (_ARRAY,n-1);

return _ARRAY[0];
}

int main()
{
    int t;
    cin >> t;
    for(int i=0;i<t;i++)>
    {
        cin >> n;

        for(int j=0;j<n;j++)>
        {
            cin >>_array[j];
        }
    }
        cout << Findmindifference();
}</iostream>