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C++

ABBY KATE C. ORIOQUE

2022

Instructor 1

Contents

Compiled Languages and C++

Hello World

Basic Language Features

Variables

Input

The Compilation Process

Source File

Source File

Object File

Object File

Executable Program inMemory

Linker Libraries

OS

Compiler

Compiler

Downloading IDE

Steps:

1. Go to this site

Downloading IDE

Steps:

2. Download the installers

Downloading IDE

Steps:

2. Click the suggested link, then save.

Downloading IDE

Steps:

4. Launch and open

Click “New Project”

Hello World

// A Hello World program

include < iostream >

int main () { std :: cout << " Hello , world !\ n "; return 0; }

Tokens!

Tokens are the minimals chunk of program that have meaning to the compiler – the smallest meaningful symbols in the language. Our code displays all 6 kinds of tokens, though the usual use of operators is not present here:

Token type Description/Purpose Examples

Operators Mathematical or logical operations

Punctuation/Separators Punctuation defining the structure of a program

Whitespace Spaces of various sorts; ignored by the compiler

Spaces, tabs, newlines, comments

Line-By-Line Explanation

1. // (Double forward-slash)

● Indicates that everything following it until the end of the line is a comment: it is ignored by the compiler.

● Another way to write a comment is to put it between /* and */

e.g. x = 1 + /sneaky comment here/

● A comment of this form may span multiple lines. Comments exist to explain non-obvious things going on in the code. Use them: document your code well!

Line-By-Line Explanation

● cout << : This is the syntax for outputting some piece of text to the screen. We’ll discuss how it works later!

● Namespaces: In C++, identifiers can be defined within a context – sort of a directory of names – called a namespace. When we want to access an identifier defined in a namespace, we tell the compiler to look for it in that namespace using the scope resolution operator (::). Here, we’re telling the compiler to look for cout in the std namespace, in which many standard C++ identifiers are defined.

A cleaner alternative is to add the following line below line 2: using namespace std ;

This line tells the compiler that it should look in the std namespace for any identifier we haven’t defined. If we do this, we can omit the std:: prefix when writing cout. This is the recommended practice.

Line-By-Line Explanation

● Strings: A sequence of characters such as Hello, world is known as a string. A string that is specified explicitly in a program is a string literal.

● Escape sequences: The \n indicates a newline character. It is an example of an escape sequence – a symbol used to represent a special character in a text literal. Here are all the C++ escape sequences which you can include in strings:

Line-By-Line Explanation

● return 0 indicates that the program should tell the operating system it has completed successfully. This syntax will be explained in the context of functions; for now, just include it as the last line in the main block. 4

Note:

Every statement ends with a semicolon (except preprocessor commands and blocks using {}). Forgetting these semicolons is a common mistake among new C++ programmers.

Values and Statements

• A statement is a unit of code that does something – a basic building block of a program.
• An expression is a statement that has a value – for instance, a number, a string, the sum of two numbers, etc. 4 + 2, x - 1, and "Hello, world!\n" are all expressions.

Note: Not every statement is an expression. It makes no sense to talk about the value of an #include statement, for instance.