lesson 1- programmingwithc++

7/28/2019 Lesson 1- ProgrammingwithC++

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What Do you mean by a Program? A program is a set of instructions that are

grouped together to accomplish a task or tasks.

These instructions can be given to a computer.

The instructions, called machine code or assemblycode consist of things like reading and writingmemory, arithmetic operations, and comparisons.

these instructions sound simple, it is actually possible

to solve a huge group problems with them. the individual instructions that the machine actually

quite simple or low-level in computer parlance.



What do you mean by Programming?

Computer Programming is the art of making a

computer do what you want it (the computer) to do.

At the very simplest level it consists of issuing asequence of commands to a computer to achieve anobjective

Writing software, computer programs, is describinghow to do something. In its simplest form, it is a lotlike writing down the steps it takes to do something - a

process. Programming will help you learn the importance of

clarity of expression.



Programming Language A vocabulary and set of grammatical rules for instructing a

computer to perform specific tasks. “A programming language is a machine-readable artificial

language designed to express computations that can be performed by a machine, particularly a computer.Programming languages can be used to create programs

that specify the behavior of a machine, to expressalgorithms precisely, or as a mode of humancommunication.”

Many programming languages have some form of writtenspecification of their syntax and semantics

Machine Code

Program



C++ is a Programming LanguageC++ is an innovative programming language

History of C++!!! C++ is a statically typed, free-form, multi-paradigm, compiled, general-purposeprogramming language.It is regarded as a "middle-level" language, as itcomprises a combination of both high-level andlow-level language features.

It was developed by Bjarne Stroustrup starting in

1979 at Bell Labs as an enhancement to the Clanguage and originally named C with Classes.It was renamed C++ in 1983.

http://en.wikipedia.org/wiki/Statically_typed

http://en.wikipedia.org/wiki/Free-form_language

http://en.wikipedia.org/wiki/Multi-paradigm_programming_language


http://en.wikipedia.org/wiki/Compiled_language

http://en.wikipedia.org/wiki/Programming_language

http://en.wikipedia.org/wiki/High-level_programming_language

http://en.wikipedia.org/wiki/Low-level_programming_language



http://en.wikipedia.org/wiki/Bell_Labs

http://en.wikipedia.org/wiki/Bjarne_Stroustrup

http://en.wikipedia.org/wiki/C_(programming_language)





























Features of C++

C++ is a statically typed,multi-paradigm,

Compiled Language.











Static typing

A programming language is said to use static typing when type checking is performed during compile-timeas opposed to run-time.



Multi-paradigm multi-paradigm programming language is a

programming language that supports more than oneprogramming paradigm.

Ex:-

a functional language, an object-oriented language,


http://en.wikipedia.org/wiki/Functional_programming

http://en.wikipedia.org/wiki/Object-oriented_programming_language




http://en.wikipedia.org/wiki/Functional_programming




Compiled language A compiled language is a programming language

whose implementations are typically compilers(translators which generate machine code from sourcecode), and not interpreters (step-by-step executors of source code, where no translation takes place).



Source Code -

#include <iostream>

using namespace std;

int main (){

cout << "Hello World!";

return 0;

}

Output

Hello World!

We have to compile the program and execute to getthe answer.



#include <iostream> Lines beginning with a hash sign (#) are directives for

the preprocessor.

#include <iostream> tells the preprocessor to includethe iostream standard file.

iosream includes the declarations of the basicstandard input-output library in C++, and it is

included because its functionality is going to be usedlater in the program.



using namespace std; All the elements of the standard C++ library are

declared within what is called a namespace, thenamespace with the name std .

So in order to access its functionality we declare withthis expression that we will be using these entities.

This line is very frequent in C++ programs that use the

standard library, and in fact it will be included in mostof the source codes.



int main () This line corresponds to the beginning of the

definition of the main function.

The main function is the point by where all C++programs start their execution, independently of itslocation within the source code.



cout << "Hello World!"; This line is a C++ statement.

cout is the name of the standard output stream in C++,

and the meaning of the entire statement is to insert asequence of characters (in this case the Hello Worldsequence of characters) into the standard outputstream (cout, which usually corresponds to thescreen).

cout is declared in the iostream standard file withinthe std namespace.



return 0; The return statement causes the main function to

finish.

return may be followed by a return code A return code of 0 for the main function is generally

interpreted as the program worked as expected without any errors during its execution.



Second Program// my second program in C++

#include <iostream>

using namespace std;int main ()

{

cout << "Hello World! ";

cout << "I'm a C++ program";

return 0;

}



Comments Comments are parts of the source code disregarded by

the compiler. They simply do nothing. Their purpose isonly to allow the programmer to insert notes ordescriptions embedded within the source code.

C++ supports two ways to insert comments:// line comment

/* block comment */



/* my second program in C++ with more comments */

#include <iostream>

using namespace std;int main ()

{

cout << "Hello World! "; // prints Hello World!

cout << "I'm a C++ program"; // prints I'm a c++ program

return 0;

}



Identifiers and reserved words

A valid identifier is a sequence of one or more letters, digits orunderscore characters (_). Neither spaces nor punctuation marksor symbols can be part of an identifier. Only letters, digits and

single underscore characters are valid. In addition, variable identifiers always have to begin with a letter.

They can also begin with an underline character (_ ), but in somecases these may be reserved for compiler specific keywords orexternal identifiers, as well as identifiers containing twosuccessive underscore characters anywhere.

In no case can they begin with a digit.



Another rule that you have to consider when inventing your ownidentifiers is that they cannot match any keyword of the C++ languagenor your compiler's specific ones, which are reserved keywords. Thestandard reserved keywords are:

asm, auto, bool, break, case, catch, char, class, const, const_cast,continue, default, delete, do, double, dynamic_cast, else, enum,explicit, export, extern, false, float, for, friend, goto, if, inline, int, long,mutable, namespace, new, operator, private, protected, public, register,reinterpret_cast, return, short, signed, sizeof, static, static_cast, struct,

switch, template, this, throw, true, try, typedef, typeid, typename,union, unsigned, using, virtual, void, volatile, wchar_t, while



Additionally, alternative representations for some operatorscannot be used as identifiers since they are reserved words undersome circumstances:and, and_eq, bitand, bitor, compl, not, not_eq, or, or_eq, xor,xor_eq

Very important: The C++ language is a "case sensitive" language. That means that an identifier written in capital lettersis not equivalent to another one with the same name but written

in small letters. Thus, for example, the RESULT variable is notthe same as the result variable or the Result variable. These arethree different variable identifiers.

lesson 1- programmingwithc++

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