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Array class in C++

The introduction of array class from C++11 has offered a better alternative for C-style arrays. The advantages of array class over C-style array are :-

  • Array classes knows its own size, whereas C-style arrays lack this property. So when passing to functions, we don’t need to pass size of Array as a separate parameter.
  • With C-style array there is more risk of array being decayed into a pointer. Array classes don’t decay into pointers
  • Array classes are generally more efficient, light-weight and reliable than C-style arrays.

 

Operations on array :-
1. at() :- This function is used to access the elements of array.
2. get() :- This function is also used to access the elements of array. This function is not the member of array class but overloaded function from class tuple.
3. operator[] :- This is similar to C-style arrays. This method is also used to access array elements.



// C++ code to demonstrate working of array,
// to() and get()
#include<iostream>
#include<array> // for array, at()
#include<tuple> // for get()
using namespace std;
int main()
{
    // Initializing the array elements
    array<int,6> ar = {1, 2, 3, 4, 5, 6};
  
    // Printing array elements using at()
    cout << "The array elemets are (using at()) : ";
    for ( int i=0; i<6; i++)
    cout << ar.at(i) << " ";
    cout << endl;
  
    // Printing array elements using get()
    cout << "The array elemets are (using get()) : ";
    cout << get<0>(ar) << " " << get<1>(ar) << " ";
    cout << get<2>(ar) << " " << get<3>(ar) << " ";
    cout << get<4>(ar) << " " << get<5>(ar) << " ";
    cout << endl;
  
    // Printing array elements using operator[]
    cout << "The array elements are (using operator[]) : ";
    for ( int i=0; i<6; i++)
    cout << ar[i] << " ";
    cout << endl;
  
    return 0;
  
}

Output:

The array elemets are (using at()) : 1 2 3 4 5 6 
The array elemets are (using get()) : 1 2 3 4 5 6 
The array elements are (using operator[]) : 1 2 3 4 5 6 

 

4. front() :- This returns the first element of array.
5. back() :- This returns the last element of array.

// C++ code to demonstrate working of
// front() and back()
#include<iostream>
#include<array> // for front() and back()
using namespace std;
int main()
{
    // Initializing the array elements
    array<int,6> ar = {1, 2, 3, 4, 5, 6};
  
    // Printing first element of array
    cout << "First element of array is : ";
    cout << ar.front() << endl;
  
    // Printing last element of array
    cout << "Last element of array is : ";
    cout << ar.back() << endl;
  
    return 0;
  
}

Output:



First element of array is : 1
Last element of array is : 6

6. size() :- It returns the number of elements in array. This is a property that C-style arrays lack.
7. max_size() :- It returns the maximum number of elements array can hold i.e, the size with which array is declared. The size() and max_size() return the same value.

// C++ code to demonstrate working of
// size() and max_size()
#include<iostream>
#include<array> // for size() and max_size()
using namespace std;
int main()
{
    // Initializing the array elements
    array<int,6> ar = {1, 2, 3, 4, 5, 6};
  
    // Printing number of array elements
    cout << "The number of array elements is : ";
    cout << ar.size() << endl;
  
    // Printing maximum elements array can hold
    cout << "Maximum elements array can hold is : ";
    cout << ar.max_size() << endl;
  
    return 0;
  
}

Output:

The number of array elements is : 6
Maximum elements array can hold is : 6

8. swap() :- The swap() swaps all elements of one array with other.

// C++ code to demonstrate working of swap()
#include<iostream>
#include<array> // for swap() and array
using namespace std;
int main()
{
  
    // Initializing 1st array
    array<int,6> ar = {1, 2, 3, 4, 5, 6};
  
    // Initializing 2nd array
    array<int,6> ar1 = {7, 8, 9, 10, 11, 12};
  
    // Printing 1st and 2nd array before swapping
    cout << "The first array elements before swapping are : ";
    for (int i=0; i<6; i++)
    cout << ar[i] << " ";
    cout << endl;
    cout << "The second array elements before swapping are : ";
    for (int i=0; i<6; i++)
    cout << ar1[i] << " ";
    cout << endl;
  
    // Swapping ar1 values with ar
    ar.swap(ar1);
  
    // Printing 1st and 2nd array after swapping
    cout << "The first array elements after swapping are : ";
    for (int i=0; i<6; i++)
    cout << ar[i] << " ";
    cout << endl;
    cout << "The second array elements after swapping are : ";
    for (int i=0; i<6; i++)
    cout << ar1[i] << " ";
    cout << endl;
  
    return 0;
  
}

Output:

The first array elements before swapping are : 1 2 3 4 5 6 
The second array elements before swapping are : 7 8 9 10 11 12 
The first array elements after swapping are : 7 8 9 10 11 12 
The second array elements after swapping are : 1 2 3 4 5 6 

 

9. empty() :- This function returns true when the array size is zero else returns false.
10. fill() :- This function is used to fill the entire array with a particular value.

// C++ code to demonstrate working of empty()
// and fill()
#include<iostream>
#include<array> // for fill() and empty()
using namespace std;
int main()
{
  
    // Declaring 1st array
    array<int,6> ar;
  
    // Declaring 2nd array
    array<int,0> ar1;
  
    // Checking size of array if it is empty
    ar1.empty()? cout << "Array empty":
        cout << "Array not empty";
    cout << endl;
  
    // Filling array with 0
    ar.fill(0);
  
    // Displaying array after filling
    cout << "Array after filling operation is : ";
    for ( int i=0; i<6; i++)
        cout << ar[i] << " ";
  
    return 0;
  
}

Output:

Array empty
Array after filling operation is : 0 0 0 0 0 0 

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



This article is attributed to GeeksforGeeks.org

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