{"id":81403,"date":"2021-07-05T09:00:01","date_gmt":"2021-07-05T03:30:01","guid":{"rendered":"https:\/\/techvidvan.com\/tutorials\/?p=81403"},"modified":"2021-07-05T09:00:01","modified_gmt":"2021-07-05T03:30:01","slug":"arrays-in-cpp","status":"publish","type":"post","link":"https:\/\/techvidvan.com\/tutorials\/arrays-in-cpp\/","title":{"rendered":"Arrays in C++"},"content":{"rendered":"

In this article, we will be learning how to work with arrays in C++. An array is a set of values of the same data type stored in contiguous memory locations.<\/p>\n

Let\u2019s suppose we need to store 10 values of int type, instead of declaring 10 different variables, we can declare an int array of size 10.<\/p>\n

C++ Array Declaration and Initialization<\/h3>\n

Syntax:<\/strong><\/p>\n

datatype arrayname[size];<\/pre>\n
For example, we can declare an array named arr that can store 10 elements of int data type as:
\nint arr[10];<\/p>\n
We can initialize an array while declaring it.<\/p>\n
Array declaration and initialization can be done in following ways:<\/p>\n
1. Specifying size<\/strong><\/p>\n
int arr[5] = {5,2,6,9,12};<\/p>\n
arr[0]<\/span> \u00a0 \u00a0 arr[1]<\/span>\u00a0 \u00a0 arr[2]<\/span> \u00a0 arr[3]<\/span> \u00a0 arr[4]<\/span><\/p>\n\n\n\n
5<\/span><\/td>\n2<\/span><\/td>\n6<\/span><\/td>\n9<\/span><\/td>\n12<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u00a0 \u00a0 \u00a0 0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a01<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a02<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 3<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a04<\/span><\/p>\n
2. Without specifying size<\/strong><\/p>\n
int arr[] = {5,2,6,9,12};<\/p>\n
This will also result in the same array as shown above.<\/p>\n
3. Initializing fewer elements than specified size<\/strong><\/p>\n
In this case, remaining elements store the default value (for fundamental data types, it is 0).<\/p>\n
int arr[5] = {5,2,6};<\/p>\n
arr[0]<\/span>  \u00a0 \u00a0 \u00a0 arr[1]<\/span>  arr[2]<\/span>  \u00a0 \u00a0 \u00a0 arr[3]<\/span> \u00a0 arr[4]<\/span><\/p>\n\n\n\n
5<\/span><\/td>\n2<\/span><\/td>\n6<\/span><\/td>\n0<\/span><\/td>\n0<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u00a0 \u00a0 \u00a0 \u00a0 0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 1<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a02<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a03<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a04<\/span><\/p>\n
4. No value in initializer<\/strong><\/p>\n
int arr[5] = { };<\/p>\n
This will result in an array arr of size 5 whose each element initially contains zero.<\/p>\n
arr[0]<\/span>  \u00a0 \u00a0 \u00a0 arr[1]<\/span>\u00a0 \u00a0 \u00a0arr[2]<\/span> \u00a0 \u00a0 \u00a0arr[3]<\/span> \u00a0 arr[4]<\/span><\/p>\n\n\n\n
0<\/span><\/td>\n0<\/span><\/td>\n0<\/span><\/td>\n0<\/span><\/td>\n0<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u00a0 \u00a0 \u00a0 \u00a0 0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a01<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 2<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 3<\/span> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 4<\/span><\/p>\n
Data Type<\/strong>
\nAn array in C++ can contain elements of any data type including int, float, double, char, etc. except void.<\/p>\n
Accessing Array Elements in C++<\/h3>\n
We can access an array element using its index. Index of an array starts from 0 and ends at (size-1).
\nSyntax<\/strong>:<\/p>\n
arrayname [index];<\/pre>\n
Example of accessing array elements in C++<\/strong><\/p>\n
\/\/program to change value of an array element\n#include <iostream>\nusing namespace std;\n\nint main() {\n  int arr[5] = {3,7,10,9,14};\n  \n  \/\/changing value of 3rd element\n  arr[2] = 11;\n  \n  \/\/Displaying third value\n  cout<<arr[2];\n  \n  return 0;\n}\n<\/pre>\n
Output<\/strong><\/p>\n
11<\/div>\n
Example to store user inputs in an array and display array elements<\/strong><\/p>\n
#include <iostream>\nusing namespace std;\n\nint main() {\n  int arr[5];\n  \n  \/\/Taking inputs from user and storing in arr\n  cout<<\"Enter 5 values\"<<endl;\n  for(int i=0; i<5; i++)\t{\n      cin>>arr[i];\n  }\n  \n  \/\/Displaying array elements\n  for(int i=0; i<5; i++)\t{\n      cout<<arr[i]<<\" \";\n  }\n  return 0;\n}\n<\/pre>\n
Output<\/strong><\/p>\n
Enter 5 values
\n1
\n3
\n5
\n6
\n2
\n1 3 5 6 2<\/div>\n
Multidimensional Arrays in C++<\/h3>\n
Multidimensional array can also be referred to as an array of arrays.<\/p>\n
We can think of a 2-Dimensional array as a table of elements of the same data type. Let us declare a 2-D array for better understanding.<\/p>\n
int x[3][4];<\/p>\n
This array contains 12 elements (as 3 * 4 = 12) of int data type. It can be thought of as a table having 3 rows and 4 columns, where each row is an array of 4 elements in itself.<\/p>\n
Example to initialize a 2-D array and access its element<\/strong><\/p>\n
#include <iostream>\nusing namespace std;\n\nint main() {\n    \t\/\/Initializing\nint arr[2][4] = {{2,9,4,6}, {1,10,8,5}};\n  \/\/Displaying 3rd element of 1st row\n  cout<<arr[0][2];\n  \n  return 0;\n<\/pre>\n
Output<\/strong><\/p>\n
4<\/div>\n
Passing Array to a Function in C++<\/h3>\n
When we pass an array to a function in C++, the function treats it as a pointer. This means that the actual array is accessed from inside the function.<\/p>\n
Example of passing array to a function<\/strong><\/p>\n
#include <iostream>\nusing namespace std;\n\nvoid display(int a[], int n) {\n    cout<<\"Elements of array are: \"<<endl;\n    for(int i=0; i<n; i++) {\n        cout<<a[i]<<\" \";\n    }\n}\nint main() {\n  int arr[5] = {1, 2, 4, 8, 16};\n  unsigned int n = sizeof(arr)\/sizeof(arr[0]);     \/\/to get number of elements in array\n  display(arr, n);\n  \n  return 0;\n}\n<\/pre>\n
Output<\/strong><\/p>\n
Elements of array are:
\n1 2 4 8 16<\/div>\n
In the above example, we have declared the formal parameter as an unsized array. This can also be declared as a pointer or a sized array.<\/p>\n
For example:<\/strong><\/p>\n
void display(int *a, int n) {\n  \/\/statements\n}\nor\nvoid display(int a[5]) {\n  \/\/statements\n}\n<\/pre>\n
In each of these three ways, the result obtained will be the same, as each indicates an integer pointer to the compiler.<\/p>\n
Pointer to an Array in C++<\/h3>\n
An array and its elements can be accessed using pointers.<\/p>\n
Example of pointer to an array in C++<\/strong><\/p>\n
#include <iostream>\nusing namespace std;\n\nint main() {\n  int arr[3] = {2, 4, 8};\n  int *p;\n  p = arr;        \/\/pointer p points to 0th element\n  cout<<*p<<endl;\n  \n  \/\/To display all elements\n  for(int i=0; i<3; i++) {\n      cout<<*(p+i)<<\" \";\n  }\n  \n  return 0;\n}\n<\/pre>\n
Output<\/strong><\/p>\n
2
\n2 4 8<\/div>\n
In this example, pointer p points to the 0th element of the array. However, we can also declare a pointer that points to an entire array.<\/p>\n
For example<\/strong>
\nint (*ptr)[3];<\/p>\n
This pointer ptr points to an array of 3 integers.<\/p>\n
Example to illustrate implementation of pointer pointing to an entire array<\/strong><\/p>\n
#include <iostream>\nusing namespace std;\n\nint main() {\n  int arr[3] = {2, 4, 8};\n  int (*p)[3];\n  p = &arr;        \/\/pointer p points to entire array\n  for(int i=0; i<3; i++) {\n      cout<<(*p)[i]<<endl;\n  }\n  \n  return 0;\n}\n<\/pre>\n
Output<\/strong><\/p>\n
2
\n4
\n8<\/div>\n
Advantages of Arrays in C++<\/h3>\n
Advantages of\u00a0 C++ arrays are:<\/p>\n
    \n
  • Requires less lines of code, because it enables us to create an array of numerous elements.<\/li>\n
  • Array indexes allow for random access to elements. Hence, elements are easily accessible.<\/li>\n
  • Traversing an array is simple.<\/li>\n
  • Sorting becomes simple.<\/li>\n
  • We can implement other data structures using arrays.<\/li>\n
  • 2-D arrays represent matrices.<\/li>\n<\/ul>\n
    Disadvantages of arrays in C++<\/h3>\n
      \n
    • While declaring an array, its size is fixed. We cannot modify the size of an array.<\/li>\n
    • There is wastage of memory if we declare size more than required.<\/li>\n
    • Insertion and deletion become costly as elements are needed to be shifted accordingly.<\/li>\n<\/ul>\n
      Summary<\/h3>\n
      We learnt about arrays in this article. An array is a set of values of the same data type stored in contiguous memory locations.<\/p>\n
      Elements of an array can be accessed using index. We learnt how to declare an array, and initialize and access its elements in C++ with suitable examples. Then, we also discussed multidimensional arrays, followed by advantages and disadvantages of arrays.<\/p>\n","protected":false},"excerpt":{"rendered":"
      In this article, we will be learning how to work with arrays in C++. An array is a set of values of the same data type stored in contiguous memory locations. Let\u2019s suppose we...<\/p>\n","protected":false},"author":1,"featured_media":81701,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3405],"tags":[3677,3678,3632,3679,3680],"class_list":["post-81403","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cpp","tag-advantages-of-arrays-in-c","tag-disadvantages-of-arrays-in-c","tag-multidimensional-arrays-in-c","tag-passing-array-to-a-function-in-c","tag-pointer-to-an-array-in-c"],"yoast_head":"\nArrays in C++ - TechVidvan<\/title>\n<meta name=\"description\" content=\"Learn about arrays in C++ with examples. 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