add size.md

Author: KristofferBarnerKleis

content/cpp/concepts/unordered-set/terms/size/size.md

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+---
+Title: 'size()'
+Description: 'size() returns the number of elements in a set as an int'
+Subjects:
+  - 'Code Foundations'
+  - 'Computer Science'
+Tags:
+  - 'Memory'
+  - 'Parameters'
+  - 'Script'		
+  - 'Syntax'
+CatalogContent:
+  - 'learn-c-plus-plus'
+  - 'paths/computer-science'
+---
+
+<!-- A description of the term -->
+The member function ```size()``` in ```<unordered_set>``` returns the number of elements currently stored in an unordered_set as an ```int```. If the unordered_set is empty, it returns 0.
+
+
+<!-- ##Syntax section that includes the syntax of the method and its details -->
+## Syntax
+### How to use size
+```cpp
+#include <unordered_set>
+unordered_set<dataType> set_name;
+set_name.size();
+```
+```size()``` is in the ```<unordered_set>``` header file, which needs to be included for the member function to work.
+
+**Parameters**
+
+This function does not take any parameters.
+
+
+<!-- An ##Example section that show an example of the current entry. -->
+## Example: Pattern
+This example shows how to setup an unordered_set
+```cpp
+#include <iostream>
+// Removes the need for std
+using namespace std;
+#include <unordered_set>
+
+int main() {
+	// Initializes an unordered_set
+	unordered_set<int> mySet;
+	// Inserts 10 into the unordered_set
+	mySet.insert(10);
+	// Prints the size of the unordered_set
+	cout << "Size: " << mySet.size();
+	return 0;
+}
+```
+This returns 1, because the unordered_set only has 1 element.
+
+
+## Example: How many elements are unique
+This example gives the size of the unordered_set and prints each element out.
+``` cpp
+#include <iostream>
+// Removes the need for std
+using namespace std;
+#include <unordered_set>
+
+int main() {
+  // Declares an unordered_set with duplicates
+  unordered_set<int> mySet {
+  1, 2, 3, 3, 1, 3, 2, 4, 5, 7
+  };
+  // Prints the size of the unordered_set
+  cout << "There are " << mySet.size() << " elements.\n";
+	cout << "The elements are: ";
+	for(int ele : mySet) {
+  	cout << ele << " ";
+	}
+  return 0;
+}
+```
+This returns 6, because an unordered_set cannot contain duplicates. The unique elements are: 7, 5, 4, 3, 2, 1
+
+
+<!-- An ## Codebyte section that have a compilable code inside it showing the current entry in use. Use ```codebyte/cpp to add compilable code. -->
+## Codebyte example
+The following code shows the distinction between ```size()``` and ```sizeof()```: ```size()``` gives the total number of elements in the unordered_set, while ```sizeof()``` gives the total memory in bytes of the unordered_set. 
+Try and change the number of iterations.
+
+```codebyte/cpp
+#include <iostream>
+// Removes the need for std
+using namespace std;
+#include <unordered_set>
+
+int main() {
+  // Initializes an unordered_set
+  unordered_set<int> mySet;
+  // Adds elements to the unordered_set
+  for (int i = 0; i < 10; i++) {
+  mySet.insert(i);
+  }
+  cout << "Number of elements: " << mySet.size() << "\n";
+  cout << "The set's byte usage: " << sizeof(mySet);
+  return 0;
+}
+```