The document presents advanced features of C++, including overloaded operators, templates, exception handling, namespaces, and the Standard Template Library (STL). It explains the concepts and provides code examples to illustrate how these features enhance programming capabilities. The document also highlights the importance of templates and exception handling for robust coding practices.

1. 1
C++ Advanced
Features
Trenton Computer Festival
March 17, 2018
Michael P. Redlich
@mpredli
about.me/mpredli/

2. Who’s Mike?
• BS in CS from
• “Petrochemical Research Organization”
• Java Queue News Editor, InfoQ
• Ai-Logix, Inc. (now AudioCodes)
• Amateur Computer Group of New Jersey
2

3. Objectives
• Overloaded Operators
• Templates
• Exception Handling
• Namespaces
• Introduction to the Standard Template
Library (STL)
3

4. Overloaded Operators
4

5. What are Overloaded
Operators?
• Define basic operations for objects of user-
defined types
• as if they were built-in types
• Often referred to as “syntactic sugar”
5

6. 6
// String.h - a simple string class
class String {
private:
char *string;
public:
String(char const *str) {
string = new char[strlen(str) + 1];
strcpy(string,str);
}
~String(void) {
delete[] string;
}
char *getString(void) const {
return string;
}
};

7. 7
// main application
#include “String.h”
// create two different objects of type String
String string1 = “Hello, C++ Users Group!”;
String string2 = “Hello, Java Users Group!”;
// a conditional *without* an overloaded equality operator
if(strcmp(string1.getString(),string2.getString()) == 0)
// do this
else
// do that
// a conditional *with* an overloaded equality operator
if(string1 == string2)
// do this
else
// do that

8. Overloaded Operators
(1)
• An overloaded operator has the form:
• T [class::]operatorω(paramList)
8

9. Overloaded Operators
(2)
•string1 == string2
• interpreted as
string1.operator==(string2);
• string1 is the object in control
• string2 is the argument passed into the
operator
9

10. 10
// Equality Operator
bool string::operator==(string const &s) {
return(strcmp(
getString(),s.getString()) == 0);
}

11. Overloaded Operators
(3)
• Attractive, but can be dangerous!!
• deep vs. shallow copy
• assignment operator side effects
• The compiler automatically generates an
assignment operator if one is not explicitly
defined
• memberwise assignments
11

12. Overloaded Operators
(4)
12
“Hello, C++ Users Group!”
“Hello, Java Users Group!”
string1.string
string2.string

13. 13
// compiler-generated Assignment Operator
string &string::operator=(string const &s) {
string = s.string;
return *this;
}
// main application
string1 = string2;

14. Overloaded Operators
(5)
14
“Hello, C++ Users Group!”
“Hello, Java Users Group!”
string1.string
string2.string

15. 15
// user-defined Assignment Operator
string &string::operator=(string const &s) {
delete[] string;
string = new char[strlen(s) + 1];
strcpy(string,s);
return *this;
}
// application
string1 = string2;

16. Overloaded Operators
(6)
16
“Hello, Java Users Group!”
“Hello, Java Users Group!”
string1.string
string2.string

17. Overloaded Operators
(7)
17
Operators Than Can Be Overloaded
+ - * / % ^ & | ~ !
= < > += -+ *= /= %= ^= &=
|= << >> >>= <<= != <= >= &&
|| ++ -- ‘ ->* -> () []
ne
w
de
le
te

18. Overloaded Operators
(8)
18
Operators That Cannot Be Overloaded
. .* :: ?:

19. Overloaded Operators
(9)
• Limitations:
• the meaning of an operator cannot be changed
• the number of operands for an operator cannot
be changed
• operator precedence and associativity cannot be
changed
• no personal operators!!
19

20. Templates
20

21. What are Templates?
• Used for generic programming
• Two kinds:
• class templates
• member function templates
21

22. Templates (1)
• Prototypes:
• template <class T> returnType
functionName(paramList) {}
• template <class T> class
className {}
22

23. 23
// swap member functions to handle different data types
void swap(int &first,int &second) {
int temp = second;
second = first;
first = temp;
}
void swap(float &first,float &second) {
float temp = second;
second = first;
first = temp;
}
void swap(char *&first,char *&second) {
char *temp = second;
second = first;
first = temp;
}

24. 24
/*
* function template to swap two elements
* of any data type
*/
template <class T>
void swap(T &first,T &second) {
T temp = second;
second = first;
first = temp;
}

25. Templates (2)
• A template specialization is the specific use
of a template member function or class
• swap<int>(1,2);
• swap<float>(1.7,3.5);
• swap<char>(‘a’,’b’);
• swap<char *>(“Mets”,”Jets”);
25

26. Exception Handling
26

27. What is Exception
Handling?
• A more robust method for handling errors
than fastidiously checking for error codes
• error code checking is tedious and can obscure
program logic
27

28. Exception Handling (1)
• Throw Expression:
• raises the exception
• Try Block:
• contains a throw expression or a member
function that throws an exception
28

29. Exception Handling (2)
• Catch Clause(s):
• handles the exception
• defined immediately after the try block
• multiple catch clauses allowed
• no implicit data type conversions
• catch(...) catches any exception type
29

30. C++ Exception Model
• Destructors invoked for all live objects as
the stack “unwinds”
• Exception Specification
• specify what type of exception(s) a member
function will throw
• Termination vs. Resumption semantics
30

31. 31
// exception handling example
#include <string>
#include <stdexcept>
void fred(void) {
FILE *file = fopen(“filename.txt”,”rt”);
try {
if(file == NULL) { // file could not be opened
throw 1;
}
int g = george(-1);
}
catch(int e) {
cout << “ERROR: Could not open file...” << endl;
}
catch(string const message) {
cout << message << endl;
}
// other statements...
}
// continued on next slide...

32. 32
// continued from previous slide...
int george(int n) {
if(n < 0) {
string message = “ERROR: Value less than zero...”;
throw message;
}
// other statements...
return n;
}

33. C++ Exception Class
Hierarchy (1)
• exception
• logic_error (client program errors)
• runtime_error (external errors)
• bad_alloc (memory allocation errors)
33

34. C++ Exception Class
Hierarchy (2)
• exception
• bad_cast (dynamic casting errors)
• bad_exception (unexpected())
• bad_typeid (RTTI errors)
34

35. 35
// exception handling example (revised)
#include <string>
#include <stdexcept>
void fred(void) {
FILE *file = fopen(“filename.txt”,”rt”);
try {
if(file == NULL) { // file could not be opened
throw runtime_error(“ERROR: Could not open file...”);
}
int g = george(-1);
}
catch(runtime_error &re) {
cout << re.what() << endl;
}
catch(string const message) {
cout << message << endl;
}
// other statements...
}

36. Exception Handling (3)
• Do not throw exceptions:
• to indicate special return values
• in copy constructors and assignment operators
• stroustrup.com/3rd_safe.pdf
36

37. Namespaces
37

38. What are Namespaces?
• Used to prevent global naming conflicts
• All C++ standard library components are
contained within a single namespace called
std
38

39. 39
// an example of using header files from different sources
// baseball.h
...
int strike = 0;
...
// bowling.h
...
bool strike = false;
...
// main application
#include baseball.h
#include bowling.h // ERROR: strike already declared

40. 40
// an example of using header files from different sources
// baseball.h
namespace baseball {
...
int strike = 0;
...
}
// bowling.h
namespace bowling {
...
bool strike = false;
...
}
// main application
#include baseball.h
#include bowling.h // OK!

41. Namespaces (1)
• Fully-qualified member names:
• namespace name
• scope resolution operator (::)
• member name
• baseball::strike
• bowling::strike
41

42. Aliases
• Provides shorthand for the fully-qualified
namespace name
• Has the form:
• namespace m = N;
• namespace bb = baseball;
• namespace bw = bowling;
42

43. Using Directive
• Provides access to all members of a
namespace without having to write the
fully-qualified namespace member names
• Has the form:
• using namespace N;
• using namespace baseball;
• using namespace bowling;
43

44. Using Declaration
• Provides access to individual members of a
namespace without having to write the
fully-qualified namespace member names
• Has the form:
• using N::m;
• using baseball::strike;
• using bowling::strike;
44

45. Standard Template
Library (STL)
45

46. What is the STL?
• A subset of Standard C++
• First developed by HP Labs in 1994
• Three main parts:
• containers
• iterators
• algorithms
46

47. What are Containers?
• A data structure that contains a sequence
of elements
• Sequential containers:
• organize elements linearly
• Sorted associative containers:
• organize elements based on a key
47

48. Containers (1)
• Primarily chosen by how well it can
perform certain operations, such as:
• add elements to the container
• remove elements from the container
• rearrange elements within the container
• inspect elements within the container
48

49. Containers (2)
49
vector deque list set/map
insert O(n) O(n) O(1) O(nlogn)
prepend O(n) O(1) O(1) O(nlogn)
find O(n) O(n) O(n) O(nlogn)
X[i] O(1) O(1) O(n) O(n)
pointers 0 1 2 3

50. What are Iterators?
• A generalization of a C/C++ pointer
• Used to access elements within an ordered
sequence
• Considered the “glue” that tie together
containers and algorithms
50

51. Iterators
• Five types:
• input
• output
• forward
• bi-directional
• random access
51

52. 52
#include <vector>
typedef vector<int>::iterator iterator
vector<int> v(10);
for(int i = 0;i < 9;++i) {
v.push_back(i);
}
iterator current = v.begin();
iterator last = v.end();
while(current != last) {
cout << *current << “n”;
++current;
}
0 1 2 3 4 5 6 7 8
current last

53. What are Algorithms?
• Perform various operations on containers
such as:
• searching
• sorting
• transforming
53

54. Algorithms
• Non-Mutating
• binary_search
• count
• equal
• find
• Mutating
• copy
• generate
• remove
• reverse
• sort
54

55. Popular C++
Compilers
55
• Embarcadero C++ Builder XE7
• embarcadero.com/products/cbuilder
• MicrosoftVisual C++
• microsoft.com
• Intel System Studio
• software.intel.com/en-us/c-
compilers

56. Popular C++
Compilers
56
• Open Watcom 1.9 (June 2010)
• openwatcom.org

57. Local C++ User
Groups
• ACGNJ C++ Users Group
• facilitated by Bruce Arnold
• acgnj.barnold.us
57

58. Further Reading (1)
58
• C & C++ Code Capsules
• Chuck Allison
• freshsources.com
• The C++ Programming Language
• Bjarne Stroustrup
• stroustrup.com/4th.html

59. Further Reading (2)
59
• The Annotated C++ Reference Manual
• Margaret Ellis and Bjarne Stroustrup
• stroustrup.com/arm.html
• 1997 C++ Public Review Document
• C++ ISO JTC1/SC22/WG21 Committee
• open-std.org/jtc1/sc22/open/n2356

60. Upcoming Events
• ACGNJ Java Users Group
• Dr. Venkat Subramaniam
• Monday, March 19, 2018
• DorothyYoung Center for the Arts, Room 106
• Drew University
• 7:30-9:00pm
• “Twelve Ways to Make Code Suck Less”
60

61. 61
Thanks!
mike@redlich.net
@mpredli
redlich.net
slideshare.net/mpredli01
github.com/mpredli01

62. Upcoming Events
• March 17-18, 2017
•tcf-nj.org
• April 18-19, 2017
•phillyemergingtech.com
62