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# C++ Arrays

## C++ Arrays

An array is used to store a collection of data but an array as a collection of variables that are all of the same type.

Instead of declaring multiple variables and storing individual values, you can declare a single array to store all the values.

### Example

```int a;

```

In the example above, variable a was declared as an array of five integer values [specified in square brackets].

You can initialize the array by specifying the values it holds:

```int b = {12, 45, 32, 80};

```
The values are provideArrays in Loops d in a comma separated list, enclosed in {curly braces}.

## Initializing Arrays

To access array elements, index the array name by placing the element's index in square brackets following the array name.
```

int main()
{
int a[] = {12, 8, 45, 90, 80};

cout << a << endl;
// Outputs 80

cout<< a << endl;
// Outputs 45

return 0;
}

```
Run example »

## Accessing Array Elements

Index numbers can be used to assign a new value to an element.

```int c[] = {15, 12, 18, 12, 14};
b = 18;

```

## Arrays in Loops

It's occasionally necessary to iterate over the elements of an array, assigning the elements values based on certain calculations.

## Arrays in Loops

Let's declare an array, that is going to store 5 integers, and assign a value to each element using the for loop:

```int myArr;

for(int x=0; x<6; x++) {
myArr[x] = 26;
}

```
Each element in the array is assigned the value of 26. The x variable in the for loop is used as the index for the array.
```
int myArr;

for(int x=0; x<6; x++) {
myArr[x] = 26;

cout << x << ": " << myArr[x] << endl;
}

//Output
/*
0: 26
1: 26
2: 26
3: 26
4: 26
5: 26

*/

```

## Arrays in Calculations

The following code creates a program that uses a for loop to calculate the sum of all elements of an array.

```int main()
{
int arr[] = {15, 28, 89, 587, 1241};
int sum = 0;

for (int x = 0; x < 6; x++) {
sum += arr[x];
}

cout << sum << endl;

return 0;
}
Run example »

```
In the array, the first element's index is 0, so the for loop initializes the x variable to 0.

## Multi-Dimensional Arrays

A multi-dimensional array holds one or more arrays.
```type name[size1][size2]...[sizeN];
```
two-dimensional 2x6 integer array:
```int x;
```

## Two-Dimensional Arrays

Following is an array with 3 rows and 4 columns:
```int x = {
{5, 6, 7,8}, // 1st row
{5, 8, 8,2}, // 2nd row
{8, 6, 8,7} // 3nd row
};

```
You can also write the same initialization using just one row.
```
int x = {{2, 3, 4}, {8, 9, 10},{8, 6, 8,7}};
```
```    int x = {{2, 3, 4}, {8, 9, 10},{8, 6, 8,7}};
cout << x << endl;

//Outputs 8

```

## Multi-Dimensional Arrays

Arrays can contain an unlimited number of dimensions

```string threeD;

```
Arrays more than three dimensions are harder to manage.