Removing duplicates from a vector

[The illusionist mirage]

I am trying to create a program that will remove all duplicated from an array.
Example, if the input is 1,2,3,2,2,3,4,5, the output should be 1, 2, 3, 4, 5.

Here's my code:

#include<iostream>
#include<stdlib.h>

using namespace std ;

int main()
{
            system("cls") ;
            int arr[] = {1, 2, 3, 2, 2, 4, 5} ;
            int i, j, x, k, n = 7 ;
            for( i = 0 ; i < n ; i++ )
            {
                        x = arr[i] ;
                        for( j = i + 1 ; j < n ; j++ )
                        {
                                    if(x== arr[j])
                                    for( k = j ; k < n ; k++ )
                                        arr[k] = arr[k+1] ;                       
                        }
                        n-- ;
            }
            for( i = 0 ; i < n ; i++ )
                cout<<arr[i]<<" " ;
            return 0 ;
}

But the above code is not giving the desired output. Please suggest corrections. Thank you.

[vlad from moscow]

#include <iostream>
 
int RemoveDuplicates( int a[], int n )
{
    int k = 0;
    
    for ( int i = 0; i < n; i++ )
    {
        int j = 0;
        while ( j < k && a[j] != a[i] ) j++;
        if ( j == k ) a[k++] = a[i];
    }
    
    return k;
}
 
int main()
{
   int a[] = { 1, 2, 3, 2, 2, 4, 5 };
   
   std::cout << "The original array:" << std::endl;
   
   for ( int x : a ) std::cout << x << ' ';
   std::cout << std::endl;
   
   int k = RemoveDuplicates( a, sizeof( a ) / sizeof( *a ) );
   
   std::cout << "There are " << k << " unique elements" << std::endl;
   for ( int i = 0; i < k; i++ ) std::cout << a[i] << ' ';
   std::cout << std::endl;
   
   return 0;
}

[The illusionist mirage]

doesnt run errors:

mingw32-g++.exe -Wall -fexceptions -std=c++11 -std=c++0x -g -c "E:\CODE BLOCKS\qh\main.cpp" -o obj\Debug\main.o
cc1plus.exe: error: unrecognized command line option '-std=c++11'
Process terminated with status 1 (0 minutes, 0 seconds)
0 errors, 0 warnings (0 minutes, 0 seconds)

[luigibana96]

two thigs and then it works:
- the "k" for cycle must arrive to k<n-1 because inside you compare with "k+1", and you can exit from the array
- "n--" must be putted inside the "if(x== arr[j])"
allright? sorry I can't explain it better, here is the main code

int main(){
            int arr[] = {1, 2, 1, 1,3, 2, 4}, i, j, k, n = 7 ;
            for( i = 0 ; i < n ; i++ ){
                        for( j = 0 ; j < n && j!=i ; j++ ){
                                    if(arr[i]== arr[j])
                                    {
	                                    for( k = j ; k < n-1 ; k++ )
	                                        arr[k] = arr[k+1] ;
	                                 n--;
				   }
											                       
                        }
            }
            for( i = 0 ; i < n ; i++ )
                cout<<arr[i]<<" " ;
            system("pause");
            return 0 ;
}

[vlad from moscow]

@The illusionist mirage
doesnt run errors:


mingw32-g++.exe -Wall -fexceptions -std=c++11 -std=c++0x -g -c "E:\CODE BLOCKS\qh\main.cpp" -o obj\Debug\main.o
cc1plus.exe: error: unrecognized command line option '-std=c++11'
Process terminated with status 1 (0 minutes, 0 seconds)
0 errors, 0 warnings (0 minutes, 0 seconds)

This has nothing common with the code I showed. You should read error messages before report them in panic in the forum. The compiler says that it does not know such option as '-std=c++11'

[Catfish3]

How about you use std::set instead of an array?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

#include <iostream> #include <set> int main() { std::set<int> si; si.insert(1); si.insert(1); si.insert(1); si.insert(2); si.insert(2); si.insert(3); for (std::set<int>::const_iterator ci = si.begin(); ci != si.end(); ++ci) std::clog << *ci << ' '; std::clog << '\n'; }

1 2 3

[vlad from moscow]

@Catfish3
How about you use std::set instead of an array?

It is another task.

[The illusionist mirage]

@vlad from moscow

you were right. I messed up with some build preferences and ended up with that message. I'll be more careful next time. Thanks for your help.