c++ - stack depth for quicksort -

i using tail recursive version of quicksort here code

  #include <iostream> using namespace std;  int partition(int a[],int l,int r){     int pivot=a[l];      std::swap(a[pivot],a[r]);       int store=l;        (int i=l;i<r;i++){            if (a[i]<=pivot){                std::swap(a[i],a[store]);            store=store+1;            std::swap(a[store],a[r]);            }         }         return store; } void tail_quick(int a[],int p,int r){      while(p<r){      int  q=partition(a,p,r);      tail_quick(a,p,q-1);      p=q+1;     } } int main(){     int a[]={21,10,13,8,56,9,34,11,22,44};     int n=sizeof(a)/sizeof(int);     tail_quick(a,0,n-1);      (int i=0;i<n;i++)          cout<<a[i]<<"  ";         return 0; } 

but output not correct not sorted , randome numbers in output please help

you using uninitialized variable in call partition below. sure shouldn't else?

void tail_quick(int a[],int p,int r){      while(p<r){      int  q=partition(a,p,q); // <--- uninitialized variable "q"      tail_quick(a,p,q-1);       p=q+1;     } }