COMPUTER PROGRAMMING

Computer programming the objective of the module to gain the necessary skills to develop a computer program using one of the high level language.

Introduction What is a computer? a computer is a device that accepts information (in the form of digitalized data) and manipulates it for some result based on a program or sequence of instructions on how the data is to be processed. What is a computer program? Sets of instructions that control computer’s processing of data, which are carried out to perform an intended task.

what are computers used for? Data processing: for commercial and financial purposes ( such as billing, shipping and receiving) Scientific processing: to support science ( raw data analysis, modelling natural phenomenon) Multimedia: (composing music, performing music, recording music, editing film and video, special effects, animation, illustration, laying out print materials, etc.)

Parts of a computer Computers’ parts can be divided into five elements: Arithmetic and logic unit(ALU). Central processing unit(CPU). Main storage. Input unit. Output unit.

Arithmetic and logic unit(ALU). performs integer arithmetic and logic operations. other specialized operations. Central processing unit(CPU). “Administrative” section Supervises and coordinates other sections of computer. contains an arithmetic/logic unit (ALU), control unit and internal buses. Main storage. called memory or internal memory. RAM (Random Access Memory)( static or dynamic) ROM (Read Only Memory) also is random.

Input unit. “Receiving” section Obtains information from input devices such as Keyboard, mouse, microphone, scanner, networks. Output Unit Shipping” section Takes information processed by computer Places information on output devices Screen, printer, networks, …

Software What is the software? Programs that run on computer.

Classification of the software operating system  control the flow of data through all the computers’ units.  Mange all the computer units  Monitoring the executions of the programs  Controlling storing data on the storage units  ……….

Classification of the software Utility programs  serve the final users  Word, excel ……

Classification of the software Programming languages  Have been used to create computer programs  Example: Java, C#, C and C++.

Types of programming languages  Machine language Only language computer directly understands “Natural language” of computer Defined by hardware design –Machine-dependent Generally consist of strings of numbers –Ultimately 0s and 1s Instruct computers to perform elementary operations –One at a time Hard to understand for humans Example: –

Types of programming languages  Assembly language English-like abbreviations representing elementary computer operations Clearer to humans Incomprehensible to computers –Translator programs (assemblers) Convert to machine language Example: –LOADBASEPAY ADD OVERPAY STORE GROSSPAY

Types of programming languages  High-level languages Similar to everyday English, use common mathematical notations Single statements accomplish substantial tasks –Assembly language requires many instructions to accomplish simple tasks Translator programs (compilers) –Convert to machine language Interpreter programs –Directly execute high-level language programs Example: –grossPay = basePay + overTimePay

Examples following sentence is written using Pascal as a high level programming language “ if (x=y)and (z=w)then writeln(‘the answer is Yes’);” Notes: - Easy to understand for human. - Can not be understood by CPU. - Has to be translated to low level language.

Con. Examples following sentence belongs to assembly language as a low level programming language “ ADD XYZ” which can be translated to: add the number which is existing in the memory at the location x to the number at the location y then store the result at the location z.

Con. Example Notes: - Difficult to the programmer. - Still can not be understood by the CPU. - Needs to be translated to low level language.

Con. Example the above sentence needs to be translated to a sequence of zeros and ones (01) to be executed. if ADD is translated to 0110 x 1001 y 1010 z 1011 The sentence is going to be like and is ready to be executed.

What are Interpreters, compilers and assemblers? Interpreter: it converts each high level instruction into a series of machine instructions and then immediately run (or execute) those instructions. Compilers: convert a finished program (or section of a program) into object code. This is often done in steps. Assemblers: program which convert the symbolic instructions ( which is written in an assembly language) into object or machine code.