Chapter 3 Getting Started with C++ C++: An Active Learning Approach Todd Breedlove & Randal Albert Copyright © 2008 Jones and Bartlett Publishers All rights reserved.

3.1 C++ Basics C++ is case sensitive Average is different than average and AVERAGE All C++ reserved words are in lowercase Reserved words - identifiers that have special meaning and are a part of the language

3.1 C++ Basics Most statements terminated by a semicolon except: Function headers Preprocessor directives Control statements Preprocessor directives - commands executed by the preprocessor Preprocessor directives require the first character on the line to be a number sign (#)

3.2 Whitespace Whitespace - empty or non-visible character (i.e., space or tab), including blank lines Aids readability Readability allows a program to be more easily modified and maintained Most whitespace is ignored by the compiler

3.3 Comments Comments - lines of C++ code that are ignored by the compiler Used to document the source code for you or for other programmers Aid in the readability and maintainability of source code

3.3 Comments Two forms A block comment can span multiple lines // inline comment /* block comment */ A block comment can span multiple lines

3.4 The main Function Function - a group of related statements that perform a specific task or job The main function (commonly referred to as “main”) is the starting point of a C/C++ program Every C/C++ program will have exactly one main

3.4 The main Function Function header - first line in a function definition Function definition - combination of the function header and a function body - the statements enclosed in curly braces int main() // Function header, no semicolon {// Start of function body return 0; // C++ statement, requires semicolon }// End of function body

3.4 The main Function Curly braces and parentheses always come in pairs Curly braces: Group statements together Define the beginning and ending of the function body

3.5 The #include Preprocessor Directive Predefined routine - not part of the core language but an extension to the language Part of the C++ standard Accessed through header files Preprocessor directive #include allows access to predefined routines in external or separate files - called header files

3.5 The #include Preprocessor Directive Two forms of the #include: #include <header_file> #include “header_file” First example - looks in the “include” directory specified by the compiler Used with predefined header files

3.5 The #include Preprocessor Directive Two forms of the #include: #include <header_file> #include “header_file” Example 2 - looks for the header file in a user specified location Used with user defined header files

3.5 The #include Preprocessor Directive The <iostream> header file contains predefined input and output routines #include <iostream> // Allows access to I/O routines int main() { // Outputs "Hello World!" to the screen std::cout << "Hello World!"; return 0; }

3.5.1 Namespaces namespace - allows grouping or structuring related entities inside one category cout is located in “std” namespace

3.5.1 Namespaces Ways to access routines in namespaces: Explicitly std::cout << “Hello World”; Using directive using namespace std; Using declaration using std::cout;

3.5.1 Namespaces Explicit requires use of the namespace prefix every time a routine is used Using directive allows access to all routines within a namespace Using declaration allows access to only those routines specified

3.7 C – The Differences C programmers are limited to the block style comment (/* */) with older compilers Many new C compilers allow the use of the inline comment (//) which has become part of the latest C standard

3.7 C – The Differences C uses different header files and routines for I/O Namespaces are not required to access predefined functions #include <stdio.h> // Allows access to I/O routines int main( void ) { // Outputs "Hello World!" to the screen printf( "Hello World!" ); return 0; }