Quicksort with strings

[kabuki]

I know that quicksort sorts integers, but can it also sort strings? For example, can I quicksort sort an array of fruits with members: oranges, apples, watermelons, and pears? If you could, how would you go about doing so.

[MiiNiPaa]

Quick sort is an algorithm which can sort anything you can define strict weak ordering of. If you are asking about function from C standard library, you can sort anything if you provide custom comparator function ( http://en.cppreference.com/w/cpp/algorithm/qsort ). However it is better to use std::sort algorithm ( http://en.cppreference.com/w/cpp/algorithm/sort ). It is more type safe and easier to use.

[kabuki]

This is only a snippet of the program. Is this sort correct way to go about quicksorting the last name of the students?

typedef struct Student
{
     char firstname,lastname,fullname;
     float t1,t2,t3;
}Student;

const int MAXSTUDENTS = 5;
void qsort(Student theStu[],int first,int last);

int main (void)
{
struct Student theStu;
qsort(theStu[],0,MAXSTUDENTS - 1);
}

void qsort(Student theStu,int start,int finish)
{
  int left=start,
      right=finish,
      pivot=theStu.lastname[(start+finish)/2];
  while (left < right) {
    while (theStu.lastname[left]  < pivot) left++; 
    while (theStu.lastname[right] > pivot) right--; 
    if (left <= right) {
      int temp = theStu.lastname[left];
      theStu.lastname[left] = theStu.lastname[right];
      theStu.lastname[right] = temp;
	  left++;
  	  right--;
    } 
  } 
  if (start < right) qsort(theStu,start,right);
  if (left < finish) qsort(theStu,left,finish);
}

[dhruv90]

umm... if u want to sort fruits in alphabetical order, this is one way using vectors:


#include<iostream>
#include<conio.h>
#include<vector>
#include<algorithm>
#include<ctime>
#include<cstdlib>

using namespace std;

int main()
{
vector<string>fruits ;
vector<string>:: const_iterator iter;
vector<string> :: const_iterator myiter;
fruits.push_back("pear");
fruits.push_back("apples");
fruits.push_back("watermelon");

srand(static_cast<unsigned int>(time(0)));


random_shuffle(fruits.begin(),fruits.end());

for(iter=fruits.begin();iter!=fruits.end();iter++)
{
cout<<*iter<<endl;
}

cout<<"sorted list \n";
sort(fruits.begin(),fruits.end());

for(myiter=fruits.begin();myiter!=fruits.end();myiter++)
{
cout<<*myiter<<endl;
}

getch();
}