Lecutre_1

Week 1

Algorithmization and

Programming Languages

Jumagaliyev Assylbek

asylbek.jumagaliyev@gmail.com

Introduction

About C++

Facilitates a disciplined approach to program design

C++ programs consist of pieces called classes and functions

Provides C++ Standard Library

First Program in C++: Printing a

Line of Text

Comments

-document program

-improve program readability

-ignored by compiler

-single-line comment starts with // (it terminates at the end of the current line)

-multiple-line comments starts with /* and ends with */

Preprocessor directive

-begins with a hash sign (#)

-processed before the program is compiled

-includes in the program the contents of the input/output stream header file

<iostream>

-preprocessor directives (like #include) do not end with a semicolon

int main ()

-a part of every C++ program

-is a program building block called a function

-exactly one function in every program must be main

-C++ programs begin executing at function main, independently of its location within the source code

-the keyword* int that main "returns" an integer

*A keyword is a word in code that is reserved by C++ for a specific use

BODY

-the left brace, {, must begin the body of every function

-the right brace, }, must end each function's body

-the entire line is called a statement

-instructs the computer to perform an action

-C++ statement must end with a semicolon(;)

-output and input are accomplished with streams of characters.

INPUT/OUTPUT

cin

-Standard input stream

-Normally keyboard

cout

-Standard output stream

-Normally computer screen

cerr

-Standard error stream

-Display error messages

Standard output stream object

std::cout

-“Connected” to screen

-Stream insertion operator (<<)

-Value to right (right operand) inserted into output stream

Namespace

std:: specifies using name that belongs to “namespace” std

std:: removed through use of using statements

Escape characters (\)

- Indicates “special” character output

return 0;

The return statement causes the main function to finish. return may be followed by a return code (in our example is followed by the return code with a value of zero). A return code of 0 for the main function is generally interpreted as the program worked as expected without any errors during its execution. This is the most usual way to end a C++ console program.