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Alphabetic sorting

Started by lacsap Oct 12, 2001 at 12:36 PM 13 replies 800+ views

Original Post

Oct 12, 2001 at 12:36 PM

Does anyone have a algorythm that allows you to alphabeticly sort 10-20 names that are entered by a person ? This MUST be in C++ ! thanks in advance

Nytegard

Oct 12, 2001 at 12:40 PM

Heap Sort
Quick Sort
Bucket Sort
Radix Sort

There are a lot more. All of these can be done in C++ easily.

noparity

Oct 12, 2001 at 12:42 PM

Do a search for bubble sort. It''s not the most efficient algorithm, but for 10-20 items it should be fine.

lacsap

Oct 12, 2001 at 1:00 PM

Thanks for your help, I''ll go for the bubble sort algorythm

pascal

Stoffel

Oct 12, 2001 at 1:17 PM

std::lexicographical_compare & your favorite container''s version of sort.

BeerNutts

Oct 12, 2001 at 1:22 PM

I wrote a program for someone and it does this exact thing. SortEmployeeData sorts a structure by age, then by last name. IsLessWord tells if word 1 is less alphabetically than word2

  
/********************************************************
*
* SortEmployeeData - Sorts the employee data by age
*
*********************************************************/
void SortEmployeeData(tEmployee *Employees, int NumEmployees)
{
    int i, j;
    tEmployee TempEmployee;

    // Perform Bubble sort out the array
    for( i = 0 ; i < NumEmployees ; i++ )
    {
        for( j = i+1; j < NumEmployees ; j++ )
        {
            if ( Employees[i].Age >= Employees[j].Age )
            {
                // if equal, then compare last name
                if ( Employees[i].Age == Employees[j].Age )
                {
                    // If the name is 1st alpha-wise, then don''t swap
                    if ( IsLessWord(Employees[i].cLastName, Employees[j].cLastName ))
                    {
                        continue;
                    
                    } /* endIF  */
                
                } /* endIF  */
                // Swap these two places
                TempEmployee = Employees[i];
                Employees[i] = Employees[j];
                Employees[j] = TempEmployee;
            
            } /* endIF  */
        
        } /* endFor  */
        
    } /* endFor  */
    

} // endof SortEmployeeData

/********************************************************
*
* IsLessWord - Is the 1st word less alpha-wise than second
*
*********************************************************/
int IsLessWord(char *cName1, char *cName2)
{
    int Count = 0;
    int IsLess = 0;

    // loop through comparing letters
    while((cName1[Count] != 0) && (cName2[Count] != 0))
    {
        if ( tolower(cName1[Count]) < tolower(cName2[Count]) )
        {
            // yes!
            IsLess = 1;
            break;
        
        } /* endIF  */
        else if ( tolower(cName1[Count]) > tolower(cName2[Count]) )
        {
            // Nope
            break;
            
        } 

        // otherwise, continue to next letter
        Count++;
    }

    // if we reached end of name1, then it must be lower
    if ( cName1[Count] == 0 )
    {
        IsLess = 1;
    
    } /* endIF  */

    return (IsLess);

} // endof IsLessWord

BeerNutts

Oct 12, 2001 at 3:46 PM

AP, gimme a break.

Gladiator

Oct 13, 2001 at 6:30 PM

well since beernuts already revealed the solution why i dont make it simple so all of us learn something here..

instead of writing your own comparision function there''s already strcmp() which can give you that information... take a look at strcmp() reference.. it returns 0 if the strings are the same but it can give you >0 or <0 depending on the strings'' alphabetical order... once agian it uses bubble sort..the easiest to code (good for a small number of items)

  
void sortNames( char names[][MAX_STRING_LENGTH], const int size )
{
    int done;
    do
    {
        done = 1;
        for( int i = 0; i < size-1; i++ )
        {
            if( strcmp( names[i], names[i+1] ) > 0 )
            {
                swapNames( names[i], names[i+1] );
                done = 0;
            }
        }
    } while( !done );
}

hope this helps

-------------------------------
Did someone say "banana"?

..-=gLaDiAtOr=-..

BeerNutts

Oct 15, 2001 at 10:41 AM

The only problem with Gladiator''s solution is strcmp doesn''t account for capital letters.

The string "Zipper" would be considered 1st alphabetically over the string "apple" (since ''Z'' = 90 and ''a'' = 97).

Nutts

S1CA

Oct 15, 2001 at 12:26 PM

strcmp() also doesn''t take locales into account! It operates purely on an ASCII basis. In ASCII non-English/Roman characters come after all the English/Roman ones so sorting on many European names would be incorrect!.

1) For comparisons which take the locale into account use the strcoll() function.

2) To also do the comparison in a case-insensitive way, use _stricoll().

If you need to do comparisons on Japanese, Chinese, Korean or Arabic character sets use the wide/multi character versions (_wcsicoll or _mbsicoll)

--
Simon O''''Connor
Creative Asylum Ltd
www.creative-asylum.com

lacsap

Oct 15, 2001 at 12:36 PM

Can''t I just convert the whole string to lowercase ?

lacsap

Oct 16, 2001 at 12:24 PM

I finally got the program to work !!!
I now have written my own function that checks if to strings are equal or not, a function that converts a string to lowercase characters (to avoid the ASCII trouble), and a swap function.

thanks for your help, everyone who helped me !

o0*pascal-lacsap*0o

djsteffey

Oct 16, 2001 at 2:23 PM

personally i would use the built in quicksort in c/c++.
just look up qsort(........);

"I pity the fool, thug, or soul who tries to take over the world, then goes home crying to his momma."
- Mr. T

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