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Re: Please help me with arrays

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Please help me with arrays

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Narue

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Re: Please help me with arrays

Jul 27th, 2005

>when I try to use functions to make a program, i do not know how to use arrays
On the surface, nothing changes. You declare an array as a function parameter the same way. The only difference is that you don't need the size, and it's a good idea to pass the size as a separate parameter:

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#include <iostream>

void print_array ( int a[], int size )
{
  for ( int i = 0; i < size; i++ )
    std::cout<< a[i] <<'\n';
}

int main()
{
  int a[] = {1,2,3,4,5};

  print_array ( a, 5 );
}

>I am lost on how to find that duplicate!
Rash's suggestion is the simplest (and you should use it for now), but far from the most efficient. Just as a taste of the other options, you can sort the array and then check adjacent values to see if they're the same, or you can use an existence table:

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#include <iostream>

template <typename T, int sz>
char (&array(T(&)[sz]))[sz];

void print_duplicates ( int a[], int size )
{
  int exist[10] = {0};

  for ( int i = 0; i < size; i++ )
    ++exist[a[i]];

  for ( int i = 0; i < sizeof array ( exist ); i++ ) {
    if ( exist[i] > 1 )
      std::cout<< i <<" is duplicated "
        << exist[i] - 1 <<" times\n";
  }
}

int main()
{
  int a[] = {5,4,7,6,5,6,7,8,9,3,4,5,6,7,8};

  print_duplicates ( a, sizeof array ( a ) );
}

An existence table is an array of counters, where the value in the original array is the index. By using a[0] as the index for exist, exist[5] is incremented. This is not an good method when the possible ranges are big because you need an array that can hold every possible value, but other methods (such as using a std::map can be generalized quite nicely, though you lose the linear performance.

I'm here to prove you wrong.

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Re: Please help me with arrays

Please help me with arrays

Re: Please help me with arrays