The index was outside the bounds of the array! [closed]

Question

Why prints that the index is out of bounds.
It is necessary to display the sum of all elements of the array.

static void Main(string[] args) { Console.WriteLine("введите кол-во значений в массиве:"); int n = int.Parse(Console.ReadLine()); double[] a = new double[n]; Random rnd = new Random(); for (int i = 0; i < a.Length; i++) { a[i] = rnd.Next(1, 100); Console.Write("{0: 0}", a[i]); } Console.WriteLine(); double max = a.Max(); Console.WriteLine("Максимальное:{0}", max); double min = a.Min(); Console.WriteLine("Минимальное:{0}", min); double sum = 0; for (int i = 0; i <= n; i++) { sum += a[i]; } Console.WriteLine("Сумма м/у мах и мin:{0} ", sum); Console.ReadLine(); }

As a result of the code execution I get an error on the line: sum + = a [i];

If you are given an exhaustive answer, mark it as correct (a daw opposite the selected answer).

Alexander Alexander 3,222 one four 15 · Answer 1 · 2016-11-20T15:31:36

 for (int i = 0; i <= n; i++) { sum += a[i]; }

change to

 for (int i = 0; i < n; i++) { sum += a[i]; }

Alexander

3,222 one four 15

Thank you very much! I corrected everything else .. - roy34
@ roy34 thank the person not only in words, but in deed - check the box next to this answer and close the question, and add points to the person. - Bulson

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Vlad from Moscow Vlad from Moscow one · Answer 2 · 2016-11-20T15:42:16

The reason for the error is that you are trying to use indexes where it is not required. As a result, when you do it yourself, you can make an inaccuracy or typo.

Since you created an array containing n elements, the allowable range of indices [0, n-1]

  for (int i = 0; i <= n; i++) ^^^^^^^ { sum += a[i]; }

therefore it would be better to write

 foreach ( var x in a ) sum += x;

without referring to indices. :)

Answer 3 · 2016-11-21T13:10:59

As said earlier, the problem is in the line: for (int i = 0; i <= n; i++) .

To solve this problem, I would have approached a bit from the other side. When iterating through a collection, you can use not third-party variables that may be erroneous, but the length of the array. You used it in the first for .

For example, if n = 10 , and in the array you have nine elements, then you will again get an exception. Suddenly the variable n has changed somewhere?

You can use Length (for lists Count ). Like this:

 for (int index = 0; index < arr.Length; index++) {...} // в случае с массивом for (int index = 0; index < lst.Count; index++) {...} // в случае со списком

The foreach, in method for iterating a colection is also very convenient if you do not need indexes, in which case you do not need to worry about knowing the number of array elements:

 foreach (var item in array) {...}

However, it should not be used to add or remove items from the original collection to avoid unforeseen side effects. If you need to add or remove items from the original collection, you should use a for loop.

foreach bit simpler, since it works for arrays or collections of objects that implement the IEnumerable or IEnumerable<T> interface from System.Collections.Generic .

But this is not all that can facilitate the work of the programmer, there is also an Enumerable.Sum method that calculates the sum of a sequence. And you do not have to go through all the elements of the collection. For example:

 double sum = a.Sum(); // сумма элементов Вашего массива

You can also note the Enumerable.Aggregate method, which applies an aggregate function to a sequence. For example, the receipt of the amount will be as follows:

 double sum = a.Aggregate((result, item) => result + item);

But this is an alternative when they are not needed and you need to sort out the collection.

The index was outside the bounds of the array! [closed]

Closed due to the fact that off-topic participants Denis , aleksandr barakin , rdorn , Alex , Alexander Petrov 23 Nov '16 at 17:27 .

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