Finding smallest value in array

Question

I need to find the smallest value which is larger than 0 among all integers stored in an array. I tried some of the ways of doing that on stackoverflow, but my minimal value still equals to 0 in all cases. What should I change in my code to make it work?

int[] userInput = new int[1000];
        int counter;

        Console.WriteLine ("Please input some numbers");

        for (counter = 0; counter < userInput.Length; counter++) {
            string line = Console.ReadLine ();

            if (line == "" || line == "stop") {
                break;
            } else {
                int.TryParse (line, out userInput [counter]);
            }
        }
        int min = 0;
        for(int i = 0; i < userInput.Length; i++)
        {
            if(userInput[i] > 0)
            {
                userInput[i] = min;
                break;
            }
        }
        for(int i = 0; i < userInput.Length; i++)
        {
            if(userInput[i] < min && userInput[i] > 0)
            {
                min = userInput [i];
            }
        }
        Console.WriteLine(min);
    }
}

}

I would like to do it without using LINQ.

The first for loop overwrites all values that are greater than 0 with 0. After that, it's no wonder, that you get 0 as the result... — Daniel Hilgarth
– Daniel Hilgarth, Commented Sep 2, 2013 at 12:19
are you getting correct values in your input array? since you are using int.TryParse and if an exception happens while converting the "line" the array will be filled with 0's. — wizzardz
– wizzardz, Commented Sep 2, 2013 at 12:19
People remove the important note while editing the question: I would like to do it without using LINQ. — L.B
– L.B, Commented Sep 2, 2013 at 12:26

Sri Harsha Chilakapati · Accepted Answer · 2013-09-02 12:38:22Z

2

An example. You can use Praveen's answer but this is just an alternative.

int[] numbers = { -1, 0, 1, 2, 3, 4, 5 };

public int getMinimum(int[] array)
{
    // Since you need larger than 0
    int minimum = 1;

    foreach (int elem in array)
    {
        minimum = Math.Min(minimum, elem);
    }

    return minimum;
}

So calling getMinimum(numbers) will return 1

Hope it helps.

edited Sep 2, 2013 at 12:38

answered Sep 2, 2013 at 12:28

Sri Harsha Chilakapati

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Comments

Sri Harsha Chilakapati · Accepted Answer · 2013-09-02 12:36:30Z

1

int[] userInput = new int[1000];
int counter;

Console.WriteLine("Please input some numbers");

for (counter = 0; counter < userInput.Length; counter++)
{
    string line = Console.ReadLine();

    if (line == "" || line == "stop")
    {
        break;
    }
    else
    {
        int.TryParse(line, out userInput[counter]);
    }
}
int min = 0;
for (int i = 0; i < userInput.Length; i++)
{
    if (userInput[i] < min && userInput[i] > 0)
    {
        min = userInput[i];
    }
}
Console.WriteLine(min);

This will be find the smallest number in array.

edited Sep 2, 2013 at 12:36

Sri Harsha Chilakapati

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answered Sep 2, 2013 at 12:35

Ambesh Kumar

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Comments

Alberto De Caro · Accepted Answer · 2013-09-02 13:04:42Z

0

Getting the max / min value among a set of values is a very popular (and eventually trivial) programming problem.

Your post is a specialized instance of the same problem. In your case you want to get the minimum positive value among a set of integers.

Your code is almost correct. Only replace the following line in the second for block:

 min = userInput[i];

edited Sep 2, 2013 at 13:04

answered Sep 2, 2013 at 12:29

Alberto De Caro

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4 Comments

I4V Over a year ago

What about if the first element is 0?

TToni Over a year ago

@I4V: The second loop searches for the first element > 0. The error in the original code is to assign min to that value instead of the other way round. After the correction, min is > 0 if a value > 0 exists in the array. The remaining loop is then correct.

TToni Over a year ago

As an optimization I would propose to limit the second and third loop to counter instead of userInput.Length (wich is always 1000). Also, the third loop could start where the second one stops.

TToni Over a year ago

Wow, three downvotes from people who can't read code... OK, OK, I'll stop the spam and move on :-)

rox · Accepted Answer · 2013-09-02 12:25:24Z

0

try this:

   int min;
    int found_positive = 0; // 1 if there's positive element
    for(int i = 0; i < userInput.Length; i++)
    {
      if(userInput[i]>0){
        if(found_positive==1){
          if(userInput[i]<min) min=userInput[i];
        }else{
          found_positive=1;
          min = userInput[i];
        }
      }
    }

answered Sep 2, 2013 at 12:25

rox

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Comments

Vandesh · Accepted Answer · 2013-09-02 12:27:51Z

0

    int[] userInput = new int[1000];
    int counter;

    Console.WriteLine ("Please input some numbers");

    for (counter = 0; counter < userInput.Length; counter++) {
        string line = Console.ReadLine ();

        if (line == "" || line == "stop") {
            break;
        } else {
            int.TryParse (line, out userInput [counter]);
        }
    }
    var min = userinput.Length>0?userInput[0]:0;
    for(int i = 1; i < userInput.Length; i++)
    {
        if(userInput[i] < min && userInput[i] > 0)
        {
            min = userInput [i];
        }
    }

This much should suffice...

answered Sep 2, 2013 at 12:27

Vandesh

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Comments

Stephane Delcroix · Accepted Answer · 2013-09-02 12:40:07Z

0

Do that with LINQ, in a single line:

int[] userInput = new int[1000];

var result = userInput.OrderBy(i=>i).SkipWhile(i=>i<=0).First()

answered Sep 2, 2013 at 12:40

Stephane Delcroix

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3 Comments

I4V Over a year ago

Have you read this part: I would like to do it without using LINQ.

Stephane Delcroix Over a year ago

yeah, but only after posting my answer :)

I4V Over a year ago

BTW: Why do you need to sort the input? userInput.Where(x => x > 0).DefaultIfEmpty().Min()

Matthias · Accepted Answer · 2013-09-02 12:42:59Z

You have to limit the list to all entries above zero and then look for the lowest minimum value which is closest to zero using the LINQ method Min(). See a non-LINQ version as a second example below.

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Please input some numbers. Use SPACE as separator");
            string line = Console.ReadLine();
            var userInput = new List<int>();

            foreach (string entry in line.Split(' '))
            {
                int number;
                if (!string.IsNullOrEmpty(entry) && int.TryParse(entry, out number))
                    userInput.Add(number);
            }

            const int lowest = 0;

            Console.WriteLine("The lowest number above {0} is: {1}", lowest, userInput.Where(n => n > lowest).Min());

            Console.WriteLine("Press any key to finish.");
            Console.ReadKey();
        }
    }
}

Non-LINQ example

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Please input some numbers. Use SPACE as separator");
            string line = Console.ReadLine();
            var userInput = new List<int>();

            int min = int.MaxValue;

            if (!string.IsNullOrEmpty(line))
            {
                foreach (string entry in line.Split(' '))
                {
                    int number;
                    if (!string.IsNullOrEmpty(entry) && int.TryParse(entry, out number))
                        userInput.Add(number);
                }
            }

            const int lowest = 0;
            foreach(int number in userInput)
            {
                if (number > lowest)
                    min = Math.Min(number, min);
            }

            Console.WriteLine("The lowest number above {0} is: {1}", lowest, min);

            Console.WriteLine("Press any key to finish.");
            Console.ReadKey();
        }
    }
}

OnABauer · Accepted Answer · 2013-09-02 12:49:12Z

0

In your current solution you change the first instance that's above 0 to 0:

if(userInput[i] > 0)
{
    userInput[i] = min;
    break;
}

You need to change it to

min = userInput[i];

Although this for loop is completely unnecessary anyway (and adds complexity). You'd be better off setting min to the maximum possible int value using int.MaxValue so that in the next for loop

if(userInput[i] < min && userInput[i] > 0)
{
    min = userInput [i];
}

the first value will be less than (or at least equal to) min;

edited Sep 2, 2013 at 12:49

answered Sep 2, 2013 at 12:33

OnABauer

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Comments

Praveen Prasannan · Accepted Answer · 2013-09-02 12:22:30Z

-1

array1.Min()

See this

With the Min method we find the minimum element or the minimum value after a transformation.

answered Sep 2, 2013 at 12:22

Praveen Prasannan

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3 Comments

Matthias Over a year ago

You have to select all values above 0 first and then use Min(). So it's array1.Where(n=>n>0).Min()

TToni Over a year ago

@Matthias: But the OP wants no LINQ

Matthias Over a year ago

@TToni He would like to ;) so no must ;) *kidding

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