Containers Added (#1942)

* Containers Added

* Text Formatting

Added required spaces between text and //

c++.html.markdown

@@ -6,6 +6,7 @@ contributors:
     - ["Matt Kline", "https://github.com/mrkline"]
     - ["Geoff Liu", "http://geoffliu.me"]
     - ["Connor Waters", "http://github.com/connorwaters"]
+    - ["Ankush Goyal", "http://github.com/ankushg07"]
 lang: en
 ---
 
@@ -985,6 +986,99 @@ cout << get<0>(concatenated_tuple) << "\n"; // prints: 10
 cout << get<3>(concatenated_tuple) << "\n"; // prints: 15
 cout << get<5>(concatenated_tuple) << "\n"; // prints: 'A'
 
+
+/////////////////////
+// CONTAINERS
+/////////////////////
+
+// Containers or the Standard Template Library are some predefined templates
+// They  manages the storage space for its elements and provide
+// member functions to access and manipulate them
+
+// Few containers are as follows:-
+
+// Vectors (Dynamic arrays)
+// Allow us to Define the Array or list of objects at run time
+#include<vector>  // will include the header file for vector
+vector< Data_Type > Vector_name; // used to initialize the vector
+cin>>val;
+Vector_name.push_back(val); // will push the value of variable into array
+
+// To iterate through vector, we have 2 choices
+// using normal looping 
+for(int i=0; i<Vector_name.size(); i++)
+// It will iterate through the vector from index '0' till last index
+
+// Using Iterator
+vector<Data_Type>::iterator it; // initialize the iteartor for vector
+for(it=vector_name.begin(); it!=vector_name.end();++it)
+
+// For accessing the element of the vector
+// Operator []
+var= vector_name[index]; //will assign value at that index to var
+
+
+// Set
+// Sets are containers that store unique elements following a specific order
+// Very useful container to store unique values in sorted order 
+// without any other functions or code
+
+#include<set>   // Will include the header file for sets
+set< int > ST;  // Will initialize the set of int data type
+ST.insert(30);  // Will insert the value 30 in set ST
+ST.insert(10);  // Will insert the value 10 in set ST
+ST.insert(20);  // Will insert the value 20 in set ST
+ST.insert(30);  // Will insert the value 30 in set ST
+// Now elements of sets are as follows
+//  10 20 30
+ 
+// To erase an element
+ST.erase(20);  // Will erase element with value 20
+// Set ST: 10 30
+// To iterate through Set we use iterators
+set< int >::iterator it;
+for(it=ST.begin();it<ST.end();it++)
+{
+	cout<<*it<<endl;
+}
+// OUTPUT: 
+// 10
+// 30
+
+// To clear the complete container we use Container_name.clear()
+ST.clear();
+cout<<ST.size();  // will print the size of set ST
+// OUTPUT: 0
+
+// NOTE: for duplicate elements we can use multiset
+
+// MAP
+// Maps store elements formed by a combination of a key value
+// and a mapped value, following a specific order
+
+#include<map>  // Will include the header file for map
+map< char, int >mymap;  // Will initalize the map with key as char and value as int
+
+mymap.insert ( pair<char,int>('A',1) );
+// Will insert value 1 for key A
+mymap.insert ( pair<char,int>('Z',26) );
+// Will insert value 26 for key Z
+
+// To iterate 
+map<char,int>::iterator it;
+for (it=mymap.begin(); it!=mymap.end(); ++it)
+    std::cout << it->first << "->" << it->second <<'\n';
+// Output: 
+// A->1
+// Z->26
+
+// To find the value correponsing to a key
+it = mymap.find('Z');
+cout<<it->second;
+
+// OUTPUT: 26
+
+
 ```
 Further Reading: