66 lines
1.9 KiB
Markdown
66 lines
1.9 KiB
Markdown
---
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title: C++ Arrays
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---
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## What are Arrays?
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An array is a series of elements of the same data type which are stored in contiguous memory locations and can be referenced individually.
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Declaration:
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dataType arrayName[arraySize];
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For example, an array containing 5 integer values called numbers is declared like so:
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```C++
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int numbers [5];
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```
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Initializiation:
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```C++
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//Initialization with entries:
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int numbers [5] = {1, 2, 3, 4, 5};
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//Initialization with no values:
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int numbers [5] = {};
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//Initialization with declaration:
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int numbers [] = {1, 2, 3, 4, 5};
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//Note that here the number of values defines the size of the array.
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//In the examples above, the size was fixed beforehand
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```
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## Types Of Arrays
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There are two types of arrays based on the way we declare it.
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**1**. Static array:
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Those arrays whose size is defined before compile time like in the examples above, are called static arrays. In these arrays we can't change their size once they are declared.
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**2**. Dynamic array:
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Dynamic arrays are those arrays, whose size is not known at compile time and we can define their size at run time. These arrays are created by using **new** keyword and when done with that array we can delete that array by using the **delete** keyword.
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### Access:
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Elements from an array can be accessed via reference of their position in the array. (Start counting from 0).
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Example:
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```C++
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x = numbers[0]; // = 1. [0] == first position
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numbers[2] = 55; // Sets the third position (3) to the new number 55
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//numbers[] is now: {1, 2, 55, 4, 5}
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```
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How to insert and print array elements:
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```C++
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int vnum[5] = {1, 2, 3, 4, 5}
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// change 4th element to 9
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vnum[3] = 9;
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// take input from the user and insert in third element
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cin >> vnum[2];
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// take input from the user and insert in (i+1)th element
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cin >> vnum[i];
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// print first element of the array
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cout << vnum[0];
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// print (i)th element of the array
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cout >> vnum[i-1];
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```
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