1. Introduction to C++
Introduced by Bjarne Stroustrup of AT&T’s Bell Laboratories in mid-1980’s
Based on C
C++ extended C to support object-oriented programming

2. Procedural Programming
Earlier programming approach
intuitive
task based
Problem was broken into manageable sub-tasks
Code was written to accomplish each sub-task
Resulting “functions” assembled to solve overall problem
Like a recipe

3. Object Oriented Programming
Newer programming approach
Data based rather than task based
Abstract objects are created
representing the data elements to be worked with
Each object is self-contained
Storing both data and procedures for manipulating the data
Details hidden from the user – i.e. a “black-box”
Objects are manipulated to solve a given problem
Advantage: “black-box” localizes software changes
Large software projects are more manageable and supportable

4. C++ Language Elements Comments Compiler directives Function main
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }
Comments
Compiler directives
Function main
Declaration statements
Executable statements
Example: miles.cpp

5. Comments
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }
// symbols indicate a line comment - apply to just the rest of the line
Block comments start with /* and end with */ - apply to as many lines as you like
Used to describe the code in English or provide non-code information
E.g. to include the name of the program or the author’s name

6. #include Compiler directive
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }
Compiler directive
Includes previously written code from a library into your program
Libraries allow for code reuse
E.g.
#include <iostream>
has operators for performing input and output within the program
The compiler knows where to locate libraries enclosed in <>
iostream will be needed in our programs in order to use cin and cout, as shown …

7. using namespace std;
Indicates to compiler that this program uses objects defined by a standard namespace called std.
i.e. a portion of the iostream library
Ends with a semicolon
Follows #include directives in the code
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }

8. Function main() Exactly one main function per program
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0;
} // end of main function
Exactly one main function per program
A function is a collection of related statements that perform a specific set of tasks
int indicates the return type of the function
( ) any input to the function would normally go here
empty parenthesis indicate that no special information is being passed to the function by the operating system

9. Types of Statements All C++ statements end with “;”
A single statement may span multiple lines
Two main types of statements
Declaration statements
describe the data the function needs:
const float KM_PER_MILE = 1.609;
float miles,
kms; (note: this is all one line!)
Executable statements
specify actions the program will take
cout << “Enter the distance in miles: “;
cin >> miles;
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }

10. Reserved Words (Keywords)
Have special meaning in C++
Cannot be used for other purposes
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }

11. Identifiers
Names for data and objects (variables) to be manipulated by the program
Must begin with a letter or underscore (not recommended)
Consist only of letters, digits, and underscores
Cannot be reserved word
Upper and lower case significant
miles.cpp
cin, cout, kms, km_per_mile, miles, std, endl
/* miles.cpp
- convert distance in miles to kilometers. */
#include <iostream> // class for stream input/output
using namespace std; // use the standard namespace
int main() // start of main function {
const float km_per_mile = 1.609; // km in a mile
float miles= -1, // input: distance in miles
kms; // output: dist in kilometers
// Get the distance in miles.
// Note: does not check if miles is valid!!! (i.e. >= 0)
cout << "Enter the distance in miles: ";
cin >> miles;
// Convert the distance to kilometers.
kms = km_per_mile * miles;
// Output the distance in miles.
cout << "The distance in miles is: " << miles << endl;
// Output the distance in kilometers.
cout << "The distance in kilometers is: " << kms << endl;
return 0; }