Re: Quicksort for list of string

From:
"Jim Langston" <tazmaster@rocketmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 19 Apr 2007 09:48:41 -0700
Message-ID:
<94NVh.39$lq2.31@newsfe04.lga>
<aparnakakkar2003@gmail.com> wrote in message
news:1176998788.073851.195740@n76g2000hsh.googlegroups.com...

On Apr 19, 8:20 pm, "Jim Langston" <tazmas...@rocketmail.com> wrote:

<aparnakakkar2...@gmail.com> wrote in message

news:1176983446.882491.29820@p77g2000hsh.googlegroups.com...

can any one tell me if I give the followiing string in input:
ABC
abc
BBC

then how I can get
ABC
abc
BBC

or

abc
ABC
BBC
as my output usiing quicksort.


Well, this doesn't use quicksort but std::sort which is O( N log N ).

Output is:

Before sort:
ABC
abc
BBC
ABCD
aB

After sort:
ABC
ABCD
BBC
aB
abc

After Case Insensitive sort:
aB
ABC
abc
ABCD
BBC

There may be a better/faster algorithm for the case insensitve comparing
of
std::strings. I just did this one rather quickly.

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cctype>

bool CILessthan( const std::string Elem1, const std::string Elem2 )
{
    for ( std::size_t i = 0; i < Elem1.length(); ++i )
    {
        if ( std::tolower( Elem1[i] ) < std::tolower( Elem2[i] ) )
            return true;
        else if ( std::tolower( Elem1[i] ) > std::tolower( Elem2[i] ) )
            return false;
    }

    // Equal up to this point, but one may be longer
    if ( Elem1.length() < Elem2.length() )
        return true;

    return false;

}

void ShowData( const std::vector<std::string>& Data )
{
    for ( std::vector<std::string>::const_iterator it = Data.begin(); it
!=
Data.end(); ++it )
        std::cout << (*it) << "\n";

}

int main()
{
    std::vector<std::string> Data;
    Data.push_back( "ABC" );
    Data.push_back( "abc" );
    Data.push_back( "BBC" );
    Data.push_back( "ABCD" );
    Data.push_back( "aB" );

    std::cout << "Before sort:\n";
    ShowData( Data );

    std::sort( Data.begin(), Data.end() );
    std::cout << "\nAfter sort:\n";
    ShowData( Data );

    std::sort( Data.begin(), Data.end(), CILessthan );
    std::cout << "\nAfter Case Insensitive sort:\n";
    ShowData( Data );

    std::string wait;
    std::getline( std::cin, wait );

}- Hide quoted text -

- Show quoted text -- Hide quoted text -

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please tell me how is it possible with (std::list<std::string> data)
as an argument


Just replace
std::sort( Data.begin(), Data.end(); CILessthan );
with
Data.sort( CILessthan );

As long as it's a list and not a vector.

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