Goodbye Duplicates! <-How to program?

Write a program that will read in N numbers, each of which is between 1 and 100, inclusive. As each number is read, print it only if it is not a duplicate of a number already read.

Specs:

Use functions for the user inputs as well as displaying the output and array manipulation.
Use c++ language.

INPUT:
The first lin of inputs is the number of inputs cases (N), which is a positive integer that does not exceed 100. the succeeding N lines specify the integers that the program reads.

OUTPUT:
Print out each unique element of thee array preceded by "#x - ", where x is the element number. Then, print out the elements with duplicates, in the order of their occurrence during input, separated by a space.

This is my current code:

Code:

---

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

using namespace std;

int inputs(int);
int numero[101];
main()
{
    int numbers;
    cin>>numbers;
    if (numbers>100 || numbers<1) { system("cls"); main(); }
    else { inputs(numbers);  }
    system("cls");
    main();
} 
int inputs(int numbers)
{
    int a;
    for (int x=1; x<=numbers; x++)
    {
        cin>>numero[x];
        if (numero[x]==numero[x]) { a=numero[x]; }
        else if (numero[x]==numero[x]) { a=numero[x]; }
    }   
    cout<<"b "<<a;
}

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First, do you know how to solve this? Apparently you will need to use an array. Do you know how you will use an array to identify duplicates? Solve that part first before you even start coding.

Once you are ready to code, do small pieces at a time. For example, you can start with an empty main. Then add the array you will need. Then add an empty input function, then fill it in with code to input the data into the array. Compile and test each step along the way. When you run into a specific problem, feel free to show your code and ask the question here.

Daved... try to check my codes it is correct for the first the?? the inputs part???
how do i compara the entered numbers so that the compiler would know which is the same and not the same??

Quote:

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system("cls"); main();

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don't call main() directly from your code

don't use endless recursion - your stack is not infinite

read while/do-while/for loops description and select suitable

Quote:

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if (numero[x]==numero[x])

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is always true
if you want to compare the new number with every number stored in the array - use loop

Code:

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if (numero[x]==numero[x]) { a=numero[x]; }
else if (numero[x]==numero[x]) { a=numero[x]; }

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So what did you want this code to do? Come up with a plan in english (or spanish or whatever) first. Follow your plan on paper to make sure it does what you want. Only when you have your plan thought up, then you should start coding it. If you want, you can post your plan for help and critiquing here.

As vart said, one idea is to loop through the existing numbers to see if the current number has been added already. See if you can use that idea as part of your plan, or come up with something different.

Code:

---

if (numero[x]==numero[x]) { a=numero[x]; }
else if (numero[x]==numero[x]) { a=numero[x]; }

---

is this the correct way to compare entered numbers??
do i need to create another loop on the same function?

Code:

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if (numero[x]==numero[x]) { a=numero[x]; }
else if (numero[x]==numero[x]) { a=numero[x]; }

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Just think logically here. E.g. if I inputted 1 in numero[x] where x=1, then numero[1]=1. And in this code, you are trying to compare between numero[x] and numero[x]. So if x=1, the code will become:

Code:

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if (numero[1]==numero[1]) { a=numero[1]; }
else if (numero[1]==numero[1]) { a=numero[1]; }

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And based on my example (numero[1]=1), it will be:

Code:

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if (1==1) { a=1; }
else if (1==1) { a=1; }

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Understand it now? BTW, don't ever call a "main()" function from a code like what vart just said. Use loop instead.

>> is this the correct way to compare entered numbers??
No.

>> do i need to create another loop on the same function?
That is one idea.

Come up with a plan in english (or spanish or whatever) first. Follow your plan on paper to make sure it does what you want. Only when you have your plan thought up, then you should start coding it. If you want, you can post your plan for help and critiquing here.

hey, this is my final code for the subject::

Code:

---

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

using namespace std;
int cstay=0, cgarb=0;
int numero[100];
int io(int);
main()
{
    int numbers;
    cin>>numbers;
    if (numbers>100 || numbers<1) { system("cls"); main(); }
    else { io(numbers);  }
    getch();
} 
int io(int numbers)
{
    int garb[cgarb], stay[cstay], temp=0;
    for (int x=0; x!=numbers; x++)
    {
        cin>>numero[x];
    }   
    for (int y=0; y!=numbers; y++)
    {
        if (temp==numero[y]) {  garb[cgarb]=numero[y]; cgarb++; }
        else { stay[cstay]=numero[y]; cstay++;}
        temp=numero[y];
    }
    system("cls");
    for (int a=0; a!=cstay; a++)
    {
       
        cout<<"#"<<a+1<<" - "<<stay[a]<<endl;
    }
    cout<<"\nDuplicates are: ";
    for (int b=0; b!=cgarb; b++)
    {
        cout<<" "<<garb[b];
    }
   
}

---

You still have errors, some of them already were mentioned.

1. don't call main directly
2. don't use global vars
3. don't use arrays of length 0
4. don't use memmory out of bound of an array
5. don't use conio.h
6. don't forget return statement in the function returning int
7. test your code. Do you think it is working?

Your definition of main is incorrect. It must be preceeded by int.

If it weren't for the specification "show array manipulation", you could just use std::list (or vector) with a search algorithm. Unfortunately, you can't. But I'm bored so I'll write this anyway:

Code:

---

#include <cstdlib>
#include <iostream>
#include <list>
#include <algorithm>

int get_num();  //returns number
bool print_num(int num,std::list<int> & nums);  //true if it prints

int main(/*stuff*/)
{
  std::list<int> nums;
  int num_of_num;

  std::cout << "How many will you be giving me?" << std::endl;
  std::cin >> num_of_num;

  int num;
  for(int c = 0; c < num_of_nums; c++)
  {
      num = get_num();  //won't return until valid number is entered
      if( print_num(num,nums) ) nums.push_back(num);
      //if the number prints, then it is new, so add it to the list
  }

  std::system("PAUSE");
  return EXIT_SUCCESS;
}

int get_num()
{
  int num;

  do {
      std::cin >> num;
  }while(num < 1 || num > 100);

  return num;
}

bool print_num(int num,std::list<int> & nums)
{
  if(std::binary_search(nums.begin(), nums.end(), num)) return false;
  else std::cout << '\t' << num << std::endl;
  return true;
}

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CodeMonkey, I am afraid your example has at least two problems. Firstly, you declare num_of_num but use num_of_nums in the for loop in main(). The other problem is that the list of numbers is not sorted, but you attempt a binary search on it.

Why use a std::list at all? From what I understand, std::vector is usually the default container, but here we can use a std::set and make use of its find() member function.

Whoops. You're right. And sorting it every time would make this program the absolute least efficient way to do this. There you go -- that's what happens when I don't follow the assignment.
Oh, list because push_back doesn't require reallocation (in a vague sense of the term). I suppose vector with a healthy reserve would be better, wouldn't it.

Actually, the re-allocation done by vector is quite efficient even without the use of reserve (see the last paragraph here: http://www.research.att.com/~bs/bs_f...low-containers).