Basic Elements of a C ++ Program

01/28/11

Quiz 1

• Monday • Chapter 1, Linux and vim• On your own – p. 24 #1-8, 13, 14, 16– odd answers in text

• Define–Memory address–Memory contents–Machine language

Objectives

• State the basic parts of a C++ program.• Create legal C++ names.• Write statements to output strings.

A Sample C++ Program

• travel.cpp

A Sample C++ Program

#include <iostream>– Preprocessor directive–Must have to do input/output– cout, cin, <<, >>

using namespace std;– Required – Used to prevent name conflicts in large

projects

travel.cpp

int main()– Beginning of first function executed–Only one main –Must be in every program

{ }– Brackets delimit executable statements

travel.cpp

double dist, time, speed;– Declare variables– Set aside locations in memory–Gives the locations names– double tells the data's type

travel.cpp

cout<< "Miles traveled?";

cin >>dist; //input – cout puts message on monitor– cin inputs data and stores it in variable,

dist.– // begins a comment

travel.cpp

speed = dist/time; //find speed• Assignment Statement• speed gets dist/time• Does computation, stores answer in

"speed"

travel.cpp

cout << speed << " mph\n"; –Outputs result to monitor– \n is newline character

return 0;– Ends program

Names • Examples: – rate, time, distance– R2D2, k9, K9, _acceration_gravity

• Contain letters, digits, underscore• Start with letter or underscore

Names

• Are these legal?Yr2007, 10_year_average, Y2K, form-99,

M_PI

Keywords• Names C++ reserves• Cannot as use variable names.• E.G. double, return, namespace• See appendix F

Output

Output

• Example -- out.cpp• cout – Console output–Output stream• destination for stream of characters

–Goes to standard output, usually monitor screen

Output

• << – insertion operator– inserts characters in output stream

• String– "September 7th is"– inserted into stream

Output

cout << “Fire”; //Leaves cursor after “e”

cout << “fighter”;

Output :

Firefighter

Output

cout << “Fire\n”; //Cursor on new line

cout << “fighter”;

Output :

Fire

fighter

• \n is an escape sequence

Output

• Program out1.cpp• several \n's

Example

Output

Output• endl– stream manipulator function.– Another way to output a newline character.– out2.cpp

Next

• Algorithms• Data Types 2.4• Input 2.3