Update : Data Structures : Arrays

Data-Structure-Arrays.md

@@ -4,6 +4,58 @@ Internally, `array` is a kind of data structure that can store a fixed-size sequ
 
 `array` consists of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.
 
+
+## Arrays in C++
+
+C++ provides a data structure, `array`, which stores a fixed-size sequential collection of elements of the same data-type. An `array` is used to store a collection of data, but it is better to think of an `array` as a collection of variables of the same type.
+
+#### Declaration of `array`
+
+```cpp
+
+int intarray[10]; // Declares an array of integer type of size 10 with elements having random values. Index ranges from 0 to 9(i.e. size-1).
+int intarray[10] = { 0 }; // Declares an array of integer of size 10 with all elements having value 0
+
+// Choose one the two declarations and then move ahead.
+
+```
+
+#### Inserting elements to `array`:
+
+```cpp
+
+intarray[0] = 1; // Inserts an integer value of 1 at index 0
+intarray[1] = 0; // Inserts an integer value of 0 at index 1
+intarray[2] = -1; // Inserts an integer value of -1 at index 2
+intarray[3] = 1; // Inserts an integer value of 1 at index 3
+
+```
+
+#### Printing an `array`:
+
+```cpp
+
+std::cout << intarray[0] << std::endl; // Returns 1 which is element at index of the array
+std::cout << intarray[11] << std::endl; // A random number is expected, while in reality this is `dangerous`, and is primary cause of crashes as it's accessing a memory location which does not exist.
+
+// To print all the elements of the array
+for(int i = 0; i < n; i++)
+	std::cout << intarray[i] << std::endl;
+
+```
+
+#### Basic operations on `array`:
+
+```cpp
+
+std::cout << sizeof(intarray)/sizeof(intarray[0]) << std::endl; // Returns the length of the array i.e. 10.
+std::cout << sizeof(intarray[0]) << std::endl; // Returns length in bytes of one array item i.e. 4 as it is an integer
+
+```
+
+:rocket: [Run Code](https://repl.it/CWZE/3)
+
+
 ## Arrays in Python
 
 Python doesn't have a native `array` data structure. An `array` in Python should not be confused with `list`. The major difference between a `list`
@@ -12,47 +64,55 @@ and an `array` in Python is that a `list` can have different types of values whe
 #### Declaration of `array`
 
 ```python
+
 from array import array
 intarray = array('i') # Declares an array of integer type
+
 ```
 
-#### Adding elements to `array`:
+#### Inserting elements to `array`:
 
 ```python
-intarray.append(1) # Adds an integer value of 1 to the array
-intarray.append(0) # Adds an integer value of 0 to the array
-intarray.append(-1) # Adds an integer value of -1 to the array
-intarray.append(1) # Again adds an integer value of 1 to the array
 
-intarray.append('d') # Would give a TypeError as the array is of integer type. 
+intarray.append(1) # Inserts an integer value of 1 to the array
+intarray.append(0) # Inserts an integer value of 0 to the array
+intarray.append(-1) # Inserts an integer value of -1 to the array
+intarray.append(1) # Inserts an integer value of 1 to the array
+
+intarray.append('d') # Would give a TypeError as the array is of integer type.
 
 #Resolve the above error and then move ahead.
+
 ```
 
-#### Printing an `array`: 
+#### Printing an `array`:
 
 ```python
+
 print(intarray) # Returns array('i', [1, 4, -1])
 print(intarray[0]) # Returns 1 which is the element at index 0 of the array
-print(intarray[3]) # Would give IndexError as there is no element at index 3 of array. 
+print(intarray[3]) # Would give IndexError as there is no element at index 3 of array.
 
 #Resolve the above error and then move ahead.
-	
+
 # To print all the elements of the array
 for i in intarray:
 	print(i)
+
 ```
 
-#### Basic operations on `array`: 
+#### Basic operations on `array`:
 
 ```python
+
 len(intarray) # Returns the length of the array i.e. 3
 intarray.itemsize # Returns length in bytes of one array item i.e. 4 as it is an integer
 intarray.count(1) # Returns the number of occurrences of 1 in the array i.e. 2
 intarray.insert(1, 3) # Insert a new item with value x in the array before position i
 intarray.remove(1) # Remove the first occurrence of 1 from the array
 intarray.reverse() # Reverse the order of the items in the array
-intarray.pop(1) # Removes the item with the index 1 from the array and returns it 
+intarray.pop(1) # Removes the item with the index 1 from the array and returns it
+
 ```
 
 :rocket: [Run Code](https://repl.it/CWJB)