Here is my code:

``````/**
* @file qsort.cpp
*
* @date 11/2/07
*
* This program implements the non recursive version of quicksort
*/

#include<iostream>
using namespace std;

/**
* Swaps two items
*
* @pre x and y are the items being swapped
* @post Contents of actual locations that x and y represent are swapped
* @param x given data item
* @param y Given data item
*/

void tSwap(int& x, int& y){
int temp = x;
x = y;
y = temp;
}//end swap

/**
* Chooses a pivot for quicksorts parition algorithm and swaps it with
* the first item in the array
*/

void choosePivot(int theArray[], int first, int last){
int pivot = last;

}//end choosePivot

/**
* Parition an array for quicksort
* @pre theArray[fist..last] is an array; fisrt <= last.
* @post Partitions theArray[fisrt..last] such that:
*  S1 = theArray[first..pivotIndex-1] < pivot
*       theArray[pivotIndex]         == pivot
*  S2 = theArray[pivotIndex+1..last] >= pivot
* @param theArray The given array
* @param first The first element to consider in theArray
* @param last The last element to consider in theArray
* @pivotIndex The index of the pivot after the partition
*/

void partition(int theArray[], int first, int last, int &pivotIndex){
//place pivot int theArray[fisrt]
choosePivot(theArray, first, last);
//copy pivot
int pivot = theArray[first];

//initially, everything but the pivot is unknown
//index of the last item in S1
int lastS1 = first;

//index of first item in unknown
int firstUnknown = first + 1;

//move one item at a time until uknown region is empty
for(; firstUnknown <= last; ++firstUnknown){
//move item from unknown to proper region
if(theArray[firstUnknown] < pivot){
//item from unknown belongs in S1
++lastS1;
tSwap(theArray[firstUnknown], theArray[lastS1]);

}//end if

//place pivot in proper posistion and mark its location
tSwap(theArray[first], theArray[lastS1]);
pivotIndex = theArray[lastS1];

}// end partition

}

/**
* Sorts the items in an array into ascending order
* @pre theArray[first..last] is an array
* @post theArray[first..last] is sorted
* @param theArray The given array
* @param first The first element to consider in theArray
* @param last The last element to consider in theArray
*/

void quicksort(int theArray[], int first, int last){

int pivotIndex;

if(first < last){
//create the partition: S1, pivot, S2
partition(theArray, first, last, pivotIndex);
quicksort(theArray, first, pivotIndex-1);
quicksort(theArray, pivotIndex+1, last);

}
}

/**
* The main method
*/

int main(){
int uArray[10] = {5, 3, 7, 9, 1, 0, 4, 8, 6, 2};

quicksort(uArray, 0, 10);

cout << "The sorted array: " << endl;

for(int i = 0; i < 10; i++){

cout << uArray[i] << endl;

}
return 0;
}``````

What I get at the end is : 1 0 2 3 4 5 6 7 8 9

Why doesnt the 0 move to the first spot?

This is what I get when I test it?

``````thwee@thwee-desktop:~\$ g++ -Wall pedantic.cc
pedantic.cc: In function ‘void choosePivot(int*, int, int)’:
pedantic.cc:33: warning: unused variable ‘pivot’
thwee@thwee-desktop:~\$ ./a.out
Segmentation fault (core dumped)``````

this is not your code. it is from carrano's book.

this is not your code. it is from carrano's book.

So you made an account, just to make this reply on a 3 year old thread? Impressive :icon_wink:
Where exactly does the OP claim that this code is his own?

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