1. COMS 261 Computer Science I
Title: C++ Fundamentals
Date: September 7, 2005
Lecture Number: 5

2. Announcements Homework Assignment Continue reading Chapter 2
Should have read 1.1 – 1.2, 2.1 – 2.5 before lab on Thursday
Read/skim the lab for Thursday
Bring lab handout to lab (class) on Thursday

3. Review Assembly Language High-Level Languages
Think – Edit – Compile – Execute - Test Cycle
Program Organization

4. Outline Code Warrior First C++ Program Area.cpp Hello, World
Implemented in Code Warrior
Project
Area.cpp

5. A First Program - Hello.cpp
// Author(s): Haul Pemler
// Date: 10/07/2005
#include <iostream>
#include <string>
using namespace std;
int main() {
cout << "Hello world!" << endl;
return 0; }
Preprocessor
directives
Comments
Provides simple access
Function named main() indicates start of program
Insertion
statement
String Literal
Ends executions
of main() which ends program
Function Definition

6. A First Program - Hello.cpp
Comments
Not executed, so use them liberally to document your code
Program and programmer name, date, what the program should do, special assumptions, input required, output produced, …
// Program: Hello
// Author(s): Haul Pemler
// Date: 10/07/2005

7. A First Program - Hello.cpp
#include <iostream>
#include <string>
Preprocessor Directives
Program executed before the compiler
Program #include means that the contents of the file named in the angle brackets should be input
Usually contains common definitions
There are other types of preprocessor directives

8. A First Program - Hello.cpp
Includes all the symbols and objects in a package
The package name is std
Package contains many common objects used by most programs
using namespace std;

9. A First Program - Hello.cpp
Defines a special function called main
It is the first function called when the program is executed
Therefore:
All C/C++ programs must have a function call main
int main() {
cout << "Hello world!" << endl;
return 0; }

10. A First Program - Hello.cpp
Functions can return a value when they are finished
The int before main () { means the function called main returns an integer
Where does the main function return the integer to?
Part of the ANSI Standard
int main() {
cout << "Hello world!" << endl;
return 0; }

11. A First Program - Hello.cpp
<< the insertion symbol (operator)
Insert the string literal “Hello, World” into an object called cout
Defined in the namespace called std
Called the standard output, stdout
cout knows to print the string (and other things) to the console
int main() {
cout << "Hello world!" << endl;
return 0; }

12. A First Program - Hello.cpp
int main() {
cout << "Hello world!" << endl;
return 0; }
endl
Manipulator defined in iostream
<< endl
Insert a carriage return into the cout object
Flush the output buffer
Print all items inserted into the cout object
; statement terminator
Identifies the end of the statement

13. A First Program - Hello.cpp
Immediately stops function execution
Communicates a value to the caller
Returning a zero from the main function means the function terminated normally
int main() {
cout << "Hello world!" << endl;
return 0; }

14. Hello Output