Lesson 2

Read the text: Fundamentals of programming and algorithmic languages.

Programming is a process of designing programs, a plan of action. The purpose of programming is to create a set of instructions that computers use to perform specific operations or to exhibit desired behaviors. It is a process of designing, writing, testing, debugging, and maintaining the source code of computer programs. This source code is written in one or more programming languages (such as Java, C++, C#, Python, etc.)

Before starting to program, it is very important to have an appreciation for how the computer is going to look at your program. When your program is executed, the computer will do nothing unless your program tells it to do so. This includes reading input from the user or a file, doing something with that input, and giving the results in a predictable manner (usually either to screen or to print).

At their core, computers are machines. Machines operate on the basis of command: you tell them to do something and they do it. This is an essential aspect of computers to be recognized by anyone who wants to program: the computer does what you tell it to do and does it faster than you could. If you do not give the computer the right commands in the expected way, you will not get the right results in the way you expect.

There are two parts to every executing program: data and code. The first is the information to be processed. The second is comprised of three kinds of statements: assignment, iteration, and operation. The kind of statement determines what the computer will do with it. This differs by programming language. No one programs in the language that the computer itself uses (binary). Instead every language is translated for the computer. The vocabulary of the programming language is a set of terms called "reserved words". Reserved words are trigger words. When the computer reads them, it triggers a response, an action. Depending on what the term is, the computer will do something immediately (e.g., 'break') or will look for more information.

Assignment statements are perhaps the simplest of the three. In assignment, the value on the right side of the equal sign ('=') is assigned to a variable name on the left.

Control statements have the sole purpose of regulating the flow of the program. Like a traffic signal, a control statement, or loop, tells the computer whether to go or stop. It does this by expressing the conditions under which an action should occur. If the conditions are not met, the entire loop is ignored by the computer.

Operation statements are the lifeblood of a program. These statements tell the computer what to do. Some commands expect to be told explicitly upon which input to act or where it should to direct the output. If this information is expected and not given, the command will be unclear to the computer, and the program will quit unexpectedly.

A programming language acts as a translator between you and the computer. Rather than learning the computer's native language (known as machine language), you can use a programming language to instruct the computer in a way that is easier to learn and understand.

A specialized program known as a compiler takes the instructions written in the programming language and converts them to machine language.

Programming a computer in an algorithmic language necessitates the availability of special software in the form of programming processors (compilers, interpreters) — which are intermediaries between the program in the algorithmic language and the machine. A complete processor executes the following functions: input of the program, lexical analysis (isolation and classification of lexemes), syntactic and semantic analysis, with indications of formal errors, synthesis of an intermediate form (representation of the program in the internal language of some abstract computer, which is convenient for the subsequent processing or execution of the program), optimization (systematic transformations of the intermediate forms which improves certain characteristics of the program such as its size, speed and demands on memory), code generation (construction of the machine program) and execution of the program.

http://python.about.com/od/throughacomputerseye/ss/begprogramming_all.htm

Ex.1. Answer the questions:

1. What is the purpose of programming? 2. What are the two parts to every executing program? 3. What is the purpose of control statements? 4. What can be considered as the lifeblood of a program.? 5. How does a programming language act? 6. What kind of functions does a complete processor execute?

Ex.2.Match the right part with the left:

1. Some commands expect to be told explicitly upon which ….	a. … that computers use to perform specific operations or to exhibit desired behaviors
2. Like a traffic signal, a control statement, or loop, tells …….	b….. a set of terms called "reserved words"
3. The vocabulary of the programming language is. …..	c… you will not get the right results in the way you expect.
4. If you do not give the computer the right commands in the expected way,.. ….	d……. the computer whether to go or stop..
5. The purpose of programming is to create a set of instructions.….	e…. input to act or where it should to direct the output.

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