# How do I return an index from an array in C#?

## How do I return an index from an array in C#?

using System;

- public static class Extensions. { public static int findIndex(this T[] array, T item) { return Array. IndexOf(array, item);
- public class Example. { public static void Main() { int[] array = { 1, 2, 3, 4, 5 };
- int index = array. findIndex(item); if (index != -1) { Console. WriteLine(String.
- } } } /*

## How do you find the index value of an array?

To find the position of an element in an array, you use the indexOf() method. This method returns the index of the first occurrence the element that you want to find, or -1 if the element is not found. The following illustrates the syntax of the indexOf() method.

**What is array indexOf C#?**

The IndexOf() method of array class in C# searches for the specified object and returns the index of the first occurrence within the entire one-dimensional Array.

**Can you use indexOf for an array?**

IndexOf(Array, Object, Int32) Searches for the specified object in a range of elements of a one-dimensional array, and returns the index of its first occurrence. The range extends from a specified index to the end of the array.

### What is the index of first element in an array?

1 Answer. Best explanation: In general, Array Indexing starts from 0. Thus, the index of the first element in an array is 0.

### How do you find indices?

k = find( X ) returns a vector containing the linear indices of each nonzero element in array X .

- If X is a vector, then find returns a vector with the same orientation as X .
- If X is a multidimensional array, then find returns a column vector of the linear indices of the result.

**How do I get the last index of an array?**

lastIndexOf() The lastIndexOf() method returns the last index at which a given element can be found in the array, or -1 if it is not present. The array is searched backwards, starting at fromIndex .

**How do you get the matching element in an integer array?**

All you need to do is iterate over the pairs of key,val multiply each key*val then sum up the multiplied values and you get your correct total. And if you need just the number of matched, you can in another variable sum up just the vals . I hope this helps!

#### What is the index of an array?

The index of a value in an array is that value’s location within the array. There is a difference between the value and where the value is stored in an array.

#### How do I get an element from an array?

get() is an inbuilt method in Java and is used to return the element at a given index from the specified Array. Parameters : This method accepts two mandatory parameters: array: The object array whose index is to be returned.

**How do I check if an array contains a value?**

For primitive values, use the array. includes() method to check if an array contains a value. For objects, use the isEqual() helper function to compare objects and array. some() method to check if the array contains the object.

**How do you check if an element is present in an array in C#?**

Use the Equals method to check if an item exists in a C# array. string subStr = “pqrs”; string[] str = { “abcd”, “ijkl”, “pqrs”, “wxyz” }; Now check whether the substring is part of the string or not using the Equals method.

## Is index same as indices?

Both “indexes” and “indices” are acceptable plural forms of the word “index” or to refer to more than one index. Index is one of those rare words that have two different plurals in English. “Indices” is originally a Latin plural, while “Indexes” has taken the English way of making plurals, using –s or –es.

## What are indices example?

Index (indices) in Maths is the power or exponent which is raised to a number or a variable. For example, in number 24, 4 is the index of 2.

**How do you find last index?**

The lastIndexOf() method returns the last index at which a given element can be found in the array, or -1 if it is not present. The array is searched backwards, starting at fromIndex .

**What is the first index of an array?**

0

1-based indexing, 0-based indexing. Note: In most programming languages, the first array index is 0 or 1, and indexes continue through the natural numbers. The upper bound of an array is generally language and possibly system specific.

### How do you check all pairs in an array?

Solution Steps

- We take a hash table of size equal to n.
- We run a loop and scan over the array X[] for each X[i]. We check if targetSum – X[i] is present in the hash table or not. If yes, we have found the pair and return it true.
- If didn’t find such a pair by end of the loop then, we return false.

### How do I get the matching elements in an integer array in CPP?

“matching elements two arrays c++” Code Answer

- bool equalelementsintwoarrays(int A[], int B[], int N) {
- sort(A, A+N);
- sort(B, B+N);
- int i = 0, j = 0;
- while (i < N && j < N) {
- if (A[i] == B[j]) return true;
- else if (A[i] > B[j]) j++;
- else i++;

**How do I get a value from an array?**

Parameters. A 32-bit integer that represents the first-dimension index of the Array element to get. A 32-bit integer that represents the second-dimension index of the Array element to get.

**How to define an array in C#?**

Searching for an Item in an Array in C#. The BinarySearch static method of the Array class can be used to search for an item in an array.

#### How do arrays work in C#?

In C#,all arrays are dynamically allocated.

#### How to find the average value of an array?

Algorithm. START Step 1 → Take an array A and define its values Step 2 → Loop for each value of A Step 3 → Add each element to ‘sum’