Topic Pre-processor cout To output a message

A sample C++ Program // sample C++ program #include <iostream> comment // sample C++ program #include <iostream> using namespace std; int main() { cout << "Hello World!"; return 0; } compiler directive use standard namespace beginning of function named main beginning of block for main output statement Pp55-58 string literal send 0 to operating system; exit main function end of block for main

cout Used to print out a message on the screen Not a keyword in C++ In order to use it, you have to include the file that defines cout --- “iostream.h” Use “#include <iostream>” to do it DEFINE BEFORE USE. pp55 – header file pp58, 443 - cout

The #include Directive Inserts the contents of another file into the program Do not place a semicolon at end of #include line pp55

g++ g++ is a 3-in-1 command A preprocessor will A preprocessor A compiler A linker A preprocessor will Remove #include directives Replace with copies of header files

using namespace std; A namespace is a collection of names. Every name has to be unique Uses standard namespace called std. Ends with a semicolon Follows #include directives in the code Must appear in all programs pp56

Function main int main ( ) { // function body return 0; } Starting point of the program Exactly one main function per program pp56-57

Function A collection of related statements Performs a specific operation int Specify return type of the function Returns an integer when function finishes ( ) Parameters of the function Empty ( ) means “no parameter needed” pp57

cout Displays output on computer screen Used together with the stream insertion operator << to send output to screen: cout << "Programming is fun!"; << can be used multiple times in an instruction cout << “Programming " << “is fun!"; Or: cout << “Programming "; cout << “is fun!"; pp58

Two ways to start a new line use the \n escape sequence (inside quotation marks) cout << "Programming is\nfun!"; Or use the endl manipulator (outside quotations marks) cout << "Programming is" << endl; cout << "fun!"; pp66

The endl Manipulator Do NOT put quotation marks around endl The last character in endl is a lowercase L, not the number 1. endl This is a lowercase L

They will produce Programming is fun!

Escape characters Used within double quotes Don’t get printed literally \n starts a new line \t inserts a tab \\ prints a backslash \ \” prints a double quote \’ prints a single quote pp66

What does this program output? // This program outputs a few sentences. #include <iostream> using namespace std; int main() { cout << “The works of Wolfgang\ninclude the following"; cout << “\nThe Turkish March” << endl; cout << “and Symphony No. 40 “; cout << “in G minor.” <<endl; return 0; } => This code will generate 5 lines of output

Structure of your program Include directives Using namespace Write all instructions inside main( ) function Compiler ignores all blank spaces except those inside quotation marks

Review C++ language elements How to use cout Section 2.1 pages 54-59, 66 How to use cout http://www.cppforschool.com/tutorial/structure-of-cpp-program.html