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Introduction to Programming Fundamentals
- 1. Lecture – 01& 02 Programming Fundamentals BY Engr. Poonam K.K
- 2. 2 Contents • Computer programming •Why programming? • Instructions and Program • Low-level, High level • Source Code and Object Code • Language Translators • Compiler • Interpreter • Assembler • Why language translators?
- 3. 3 Contents • Difference betweencompiler and interpreter • Bug and Debugging
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- 5. 5 Computer Programming • Itis the process of giving instructions (commands) to the computer to do a meaningful task. • It is an act of teaching the computer on how to do a task. • The art and science of creating instructions for a computer to follow. • Creating a sequence of instructions to enable the computer to do something.
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- 7. 7 Why Programming? • Computeris just a dumb machine made up of different electronic components. It is like a box which cannot do anything by itself. • It is the user who tells the computer “what it has to do?” • If we need our computer to perform some task, we first have to teach the computer in detail “how it will accomplish that task?” • Once the computer is taught about a particular task, it will completely obey it but cannot do anything that it is not taught to.
- 8. 8 Why Programming? • Likethe humans, we can teach the computer through communicating with it using a particular language. • The language that computer understands is machine language, also called as binary language. Machine language is the language of 0s and 1s. • We give detailed instructions to the computer to solve a particular task. Programming is the term that refers to teaching, instructing or giving commands to the computer.
- 9. 9 Why Programming? • Programmingis more about problem-solving skills than writing the code itself. • Programming teaches you how to understand, analyze, and solve problems. It enhances your analytical reasoning abilities and helps you cope with daily real- life problems as well. • Hence learning to program is important because it develops analytical and problem-solving abilities.
- 10. 10 Programmer • The personwho gives the instructions (commands) to the computer is known as the programmer. • A person who designs and writes computer programs.
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- 12. 12 Instruction • Instruction isany command given to the computer. • For example: 1) Add two variables A and B 2) Display result 3) Read file • Each of these is the individual instruction to the computer.
- 13. 13 Program NOW DO THIS! NOWDO THIS! NOW DO THIS! NOW DO THIS! NOW DO THIS!
- 14. 14 Program • Program isa set (collection) of instruction to do a meaningful task. • A sequence of instructions that are interpreted and executed by a computer. It can be made of a single or hundred of instructions. • For example: In order to teach the computer on how to calculate average of three numbers? We need to give multiple instructions to the computer to do the task.
- 15. 15 Program Instruction 1: Getfirst number from the user and store it in A variable Instruction 2: Get second number from the user and store it in B variable Instruction 3: Get third number from the user and store it in C variable Instruction 4: Add A, B, C and store the result in SUM variable Instruction 5: Divide SUM by 3 and store result in AVG variable Instruction 6: Display AVG variable • Instructions 1-6 are used to solve a single task. This collection of instruction is known as a program.
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- 17. 17 Programming Language • Aprogramming language is an artificial language designed to communicate instructions to a computer. • A programming language is a notation for writing programs. • A vocabulary and set of grammatical rules for instructing a computer to perform specific tasks.
- 18. 18 Programming Language • Eachlanguage has a unique set of keywords (special words that it understands) and a special syntax (format) for organizing program instructions. • There are many programming languages. For example: • GW Basic • C • C++ • JAVA • Pascal • COBOL • Python • C#
- 19. 19 Types of ProgrammingLanguages • There are three types of programming languages: Programming Languages Low-Level Languages High-Level Languages Middle-Level Languages
- 20. 20 Low-Level Language Machine (Computer)Human (Programmer) LANGUAGE A language which is closer to machine (computer)
- 21. 21 Low-Level Language • Alow level language is one which is closer to the machine (computer). • It is easier for machines to understand and difficult for humans to understand. • It is faster in execution as compared to high and middle level languages.
- 22. 22 Low-Level Language • Twoof the types of low-level languages are: Machine Language Assembly Language
- 23. 23 Machine Language • Itis one of the low level language. • It is the language of 0s and 1s. • Machine languages are the only languages directly understood by the computers. • While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers (0s and 1s).
- 24. 24 Machine Language • Itis the native language of the machines (computers). • Here all the instructions are written as code of binary sequence. For example: • In order to do addition, the code is: 10010001 • In order to decrement a number by one, the code is: 11011011 • In order to move data from one place to another, the code is: 10000111
- 25. 25 Machine Language • Thereare hundreds of instructions and each instruction has a binary code. • Is it possible to remember all the codes of hundreds of instruction? • Obviously not! Hence machine language almost impossible to understand.
- 26. 26 Machine Language • Machinelanguage program example: 10010010 11001010 01001010 11110101 00000101 00101000 11101010 10101010
- 27. 27 Assembly Language • Assemblylanguage is same as machine language but uses English like words to represent individual operations. • For example: Instead of binary codes it uses : ADD, MOV, SUB, INC • Assembly language is also a low-level language. • It is easier than the machine language but still it is very difficult to control a larger program using assembly.
- 28. 28 Assembly Language • Asassembly language contains English like words, which will not be understood by the computer (because it only understands 0s and 1s) • A translator first converts the assembly language program into machine language program. • Translator used with assembly language is called Assembler.
- 29. 29 Assembly Language • Assemblylanguage program example: MVI A, 05h MVI B, 9Ah ADD B INC A STA 8200h HLT
- 30. 30 High-Level Language Machine (Computer)Human (Programmer) LANGUAGE A language which is closer to human (programmer)
- 31. 31 High-Level Language • Ahigh-level language is one which is closer to the human (programmer). • It is easier for humans to understand and difficult for machines to understand. • It is slower in execution as compared to low level languages.
- 32. 32 High-Level Language • Likeassembly language, it also uses English like words for the operations. • For example: for, if, else, break, continue, while, include, using, import • It is more easier than assembly language.
- 33. 33 High-Level Language • Someof the high level programming languages are: • GW Basic • C++ • JAVA • Pascal • COBOL • Python • C# • Visual Basic • J# • Ruby • PHP
- 34. 34 High-Level Language • Highlevel language program example: int main() { int a = 5; int b = 6; if(a > b) cout<<“First number is greater.”; else cout<<“Second number is greater.”; }
- 35. 35 Middle-Level Language Machine (Computer)Human (Programmer) LANGUAGE A language which is some how closer to machine as well as human
- 36. 36 Middle-Level Language • Amiddle level language is one which is closer to machine (computer) as well as to human (programmer). • A language that has the features of both low level and high level languages. • More formally, a high level language that allows you to write low level programs in it is called as middle level language.
- 37. 37 Middle-Level Language • Someof the middle level programming languages are: • C • IBM PL/S (Programming Language/Systems) • BCPL (Basic Combined Programming Language) • BLISS (Bill's Language for Implementing System Software)
- 38. 38 Source Code andObject Code Source Code • The set of instructions written in any language other than machine language is called as source code. • It is not directly understood by the machine (computer). Object Code • The set of instructions written in machine language is called as object code. It is also known as machine code. • It is the only code which is directly understood by the machine (computer).
- 39. 39 Source Code andObject Code Source Code • It is in the form of text. • It is human readable. • It is generated by human (programmer). • It is input to the language translator. Object Code • It is in the form of binary numbers. • It is machine (computer) readable. • It is generated by the language translator. • It is the output of the language translator.
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- 41. 41 Language Translators • Languagetranslator is a program that converts the source code in to the object code. Source Code Object Code CONVERT Language Translator Translator
- 42. 42 Why Language Translators? •Computer only understands object code (machine code). • It does not understand any source code. • There must be a program that converts source code into the object code so that the computer can understand it. • The language translator is one which does this job. • The programmer writes the source code and then translator converts it in machine readable format (object code).
- 43. 43 Types of LanguageTranslators • There are three types of language translator: Language Translators Assembler Compiler Interpreter
- 44. 44 Assembler • Assembler isthe language translator that converts assembly language code in to the object code (machine code). Assembly Source Code Object Code CONVERT Assembler
- 45. 45 Compiler • Compiler isthe language translator that converts high level language code in to the object code (machine code). • It converts the whole code at a time. High-Level Source Code Object Code CONVERT Compiler
- 46. 46 Compiler Line 1 :Instruction 1 Line 2 : Instruction 2 Line 3 : Instruction 3 Line 4 : Instruction 4 Line 5 : Instruction 5 Program Line 1 : Instruction 1 Line 2 : Instruction 2 Line 3 : Instruction 3 Line 4 : Instruction 4 Line 5 : Instruction 5 Read whole Program Convert whole program in to object code Execute 1 2 3 4
- 47. 47 Interpreter • Interpreter isthe language translator that converts high level language code in to the object code (machine code). • It converts the code line by line. High-Level Source Code Object Code CONVERT Interpreter
- 48. 48 Interpreter Line 1 :Instruction 1 Line 2 : Instruction 2 Line 3 : Instruction 3 Line 4 : Instruction 4 Line 5 : Instruction 5 Program Read Line 1 Convert in to object code Execute 1 Read Line 2 Convert in to object code Execute Read Line 3 Convert in to object code Execute Read Line 4 Convert in to object code Execute Read Line 5 Convert in to object code Execute 2 3 4 5 6
- 49. 49 Difference between Compilerand Interpreter Compiler • It converts whole code at a time. • It is faster. • Requires more memory. • Errors are displayed after entire program is checked. • Example: C, C++, JAVA. Interpreter • It converts the code line by line. • It is slower. • Requires less memory. • Errors are displayed for every instruction interpreted (if any). • Example: GW BASIC, Ruby, Python
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- 51. 51 Bug • An erroror defect occurred inside a computer program or hardware that causes it to produce an incorrect or unexpected result, or to behave in unintended ways is called as a bug. • Most of the bugs arise from mistakes and errors made by programmer in source code.
- 52. 52 Bug • The termbug was used by Grace Hopper in 1946. • Hopper used to work on Mark II computer, there some error occurred in the system. The cause of the error was a moth (bug) trapped in a relay creating short circuit. • That caused the term bug to be coined.
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- 54. 54 Debugging • It isthe process of finding and fixing the bugs (errors) in the program. • It is the process of removing errors. • The programmer manually does this by examining the source code.
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