Programing Fundamental

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Programing Basic, C Programing Basic, Programing Basic for Engineers & Technologist

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Programing Fundamental

  1. 1. C Programming - Lecture 1 1 Programming Fundamentals CS-215/203 Engr. Qazi Shahzad Ali Lecture # 1
  2. 2. C Programming - Lecture 1 2 C Programming language • Developed in 1972 by Dennis Ritchie at AT & T Bell Labs (American Telephone & Telegraph Company) • Very widely used general purpose programming language • Available on many machines and operating systems • Design to be flexible and powerful • Originally a replacement for assembly language (middle- level) • C requires extreme care in programming • C++ is a superset of C
  3. 3. C Programming - Lecture 1 3 Outline and Objective 1-Program Development Cycle 2-Programming Tools
  4. 4. C Programming - Lecture 1 4 1-Program Development Cycle • Software refers to a collection of instructions for the computer • The computer only knows what to do what the programmer tells it to do • Therefore, the programmer has to know how to solve problems
  5. 5. C Programming - Lecture 1 5 Performing a Task on the Computer: Input Processing Output
  6. 6. C Programming - Lecture 1 6 Program Planning • A recipe is a good example of a plan • Ingredients and amounts are determined by what you want to bake • Ingredients are input • The way you combine them is the processing • What is baked is the output
  7. 7. C Programming - Lecture 1 7 1-Program Development Cycle: 1. Analyze Requirement: Define the problem, review the requirements. 2. Design Solution: Plan the solution to the problem (Solution algorithm or Program Logic) 3. Validate Design: Check Program design for accuracy.
  8. 8. C Programming - Lecture 1 8
  9. 9. C Programming - Lecture 1 9 1-Program Development Cycle: 4. Implement Design (Code): Translate the algorithm into a programming language (here, C). 5. Test Solution (Test and Debug): Locate and remove any errors in the program. 6. Complete the Documentation: Organize all the materials that describe the program.
  10. 10. C Programming - Lecture 1 10 2-Programming Tools: 1. Algorithms 2. Pseudo code 3. Flowchart 4. Hierarchy Chart (Structure chart)
  11. 11. C Programming - Lecture 1 11 1-Algorithm
  12. 12. C Programming - Lecture 1 12 • Step by step method of performing any task is called as Algorithm. • Breaking up a big task in to smaller steps to make it easy to perform. • Brushing teeth, making tea, getting ready for school/office are examples of some sort of algorithms • Each step of the algorithm is called as Instruction 1-Algorithm
  13. 13. C Programming - Lecture 1 13 • A step by step series of instructions for solving a problem (a recipe is an example of an algorithm) • Algorithms are key to solving many problems efficiently 1-Algorithm
  14. 14. C Programming - Lecture 1 14 • Example of making tea : Begin 1. Boil water 2. Put tea powder in the kettle 3. Pour boiled water in the kettle 4. Wait for three minutes 5. Boil milk 6. Put boiled milk in a cup 7. Add sugar to the cup 8. Empty the kettle in the cup 9. Stir the cup with a spoon End Algorithm Example
  15. 15. C Programming - Lecture 1 15 Unfortunately not every problem or task has a "good" Algorithmic solution. • Unsolvable problems - no algorithm can exist to solve the problem (Halting Problem) • "hard" (intractable) problems - algorithm takes too long to solve the problem (Traveling Salesman Problem) • Problems with no known algorithmic solution
  16. 16. C Programming - Lecture 1 16 2-Pseudo code
  17. 17. C Programming - Lecture 1 17 2-Pseudocode? • A program design technique that uses English words. • Has no formal syntactical rules. • The idea is to represent the algorithm in a form that is in between pure English and actual Running code • Actually it’s one of the way for expression of Algorithm.
  18. 18. C Programming - Lecture 1 18 What is Pseudo code? • Pseudo means “pretended” / “not real” • Code refers to a computer programming language • It is a written statement of an algorithm using a restricted and well-defined vocabulary
  19. 19. C Programming - Lecture 1 19 Pseudo code - format • Write only one statement per line • Capitalize initial keyword • Indent to show hierarchy • End multi-line structures • Keep statements language independent
  20. 20. C Programming - Lecture 1 20 Pseudocode - format • It should not be paragraphs or free-flowing sentences. • It also should not contain any language- specific syntax. • it should reflect what’s in your final program, not the ideas you scrapped along the way
  21. 21. C Programming - Lecture 1 21 Pseudo code Vocabulary 1.1. Input/outputInput/output 2.2. IterationIteration 3.3. Selection/DecisionSelection/Decision 4.4. ProcessingProcessing
  22. 22. C Programming - Lecture 1 22 1-Input/output • 1- Input – INPUT, READ – Used to get values from a data source, for example from a keyboard – INPUT age • 2- Output – DISPLAY, PRINT, WRITE – Used to output values to a data sink, a screen or printer – DISPLAY new_value
  23. 23. C Programming - Lecture 1 23 2-Iteration or Loop • FOR <var> = <start value> to <stop value> statement(s) ENDFOR • FOR count = 1 to 10 DISPLAY count ENDFOR
  24. 24. C Programming - Lecture 1 24 3-Decision • IF <condition> THEN statement END-IF • IF <condition> THEN statement ELSE statement END-IF
  25. 25. C Programming - Lecture 1 25 4-Processing • ADD – ADD 3 TO count • SUBTRACT – SUBTRACT 5 FROM count • COMPUTE – COMPUTE 10 + count GIVING result • SET – SET count TO 12
  26. 26. C Programming - Lecture 1 26 Example Original Program Specification Write a program that obtains two numbers from the user. It will print out the sum of those numbers. Pseudo code DISPLAY the message to enter the first integer READ user’s first integer input DISPLAY the message to enter the second integer READ user’s second integer input COMPUTE first integer + second integer GIVING sum DISPLAY an output message that explains the answer as the sum DISPLAY the sum
  27. 27. C Programming - Lecture 1 27 Exercise • Write Pseudocode to calculate the area of a circle • Write Pseudocode to calculate sum of first ten numbers • Write Pseudocode to calculate sum of first ten even numbers
  28. 28. C Programming - Lecture 1 28 Program Algorithm (stage 4) (pseudocode) • Set count and sum to 0 • DO WHILE there is more data Get next number: value Increment count add value to sum LOOP • IF count > 0 THEN Set average to sum/count Display average ELSE Display ‘No data!’ END IF
  29. 29. C Programming - Lecture 1 29 Examples of Pseudocode: • Fahrenheit to Celsius : 1. get a value for f-temp 2. set the value of c-temp to (5 / 9) * (f-temp - 32) 3. return the value of c-temp • Math: 1. get a value for X, Y 2. if X <= Y then 1. return the value of X 3. else 1. return the value of Y
  30. 30. C Programming - Lecture 1 30 3-Flow Chart
  31. 31. C Programming - Lecture 1 31 3-Flow Chart • Logic diagram to describe each step that the program must perform to arrive at the solution. • A popular logic tool used for showing an algorithm in graphics form.
  32. 32. C Programming - Lecture 1 32 Flowchart Symbol • Programmer prepares flowchart before coding. • Most common flowchart symbols are: Flow line Terminal Input/Ouput Decision Processing
  33. 33. C Programming - Lecture 1 33 Purpose of Flowcharting: • An aid in developing the logic of a program. • Verification that all possible conditions have been considered in a program. • Provides means of communication with others about the program. • A guide in coding the program. • Documentation for the program.
  34. 34. C Programming - Lecture 1 34 Flow Chart (using Boxes) Example of making tea: Begin Boil water Put tea powder in kettle Pour boiled water in kettleEmpty kettle in cup Wait for three minutes Put boiled milk in cup Stir the cup with a spoon Add sugar to the cup Boil milkEnd
  35. 35. C Programming - Lecture 1 35 Example of Flowchart: Ordering a Burger Algorithm 1 (Standard Process): 1. Approach Counter 2. Order Burger 3. If You Want Fries Then 1. Order Fries 4. Else, Go To Next Step 5. If You Want Drink Then 1. Order Drink 6. Else, Go To Next Step 7. Pay cashier Algorithm 2 (Improved Process): 1. Approach counter 2. Order Combo Meal 3. Pay cashier Pseudocode
  36. 36. C Programming - Lecture 1 36 Want Fries Cold Drink Approach Counter Pay Cashier Yes Yes No No Flowchart Order Burger Order Fries Order drinks
  37. 37. C Programming - Lecture 1 37 Computing The Sum, Average, and Product of Three Numbers Start Read X, Y, Z S = X + Y + Z A = S / 3 P = X x Y x Z Write S, A, P Stop Flowchart 1. READ X, Y, Z 2. COMPUTE SUM (S) As X + Y + Z 3. COMPUTE Average (A) As S / 3 4. COMPUTE Product (P) As X x Y x Z 5. WRITE (Display) the Sum, Average, and Product Pseudocode
  38. 38. C Programming - Lecture 1 38 1. READ A, B 2. IF A is less than B 1. BIG = B 2. SMALL = A 3. ELSE 1. BIG = A 2. SMALL = B 3. Write (Display) BIG, SMALL Pseudocode Example of Flowchart and Pseudocode: Determine Large/Small
  39. 39. C Programming - Lecture 1 39 Example of Flowchart and Pseudocode: Determine Large/Small 1. READ A, B 2. IF A is less than B 1. BIG = B 2. SMALL = A 3. ELSE 1. BIG = A 2. SMALL = B 3. Write (Display) BIG, SMALL Pseudocode Start Read A, B BIG = A SMALL = B Write BIG, SMALL Stop A < B? No BIG = B SMALL = A Yes Flowchart
  40. 40. C Programming - Lecture 1 40 Example of Flowchart and Pseudocode: Computing Interest on a Loan Start READ Name Balance, Rate COMPUTE Interest = Balance X Rate WRITE Name, Interest Stop 1. READ Name, Balance, Rate 2. COMPUTE Interest as balance x Rate 3. WRITE (DISPLAY) Name And Interest Pseudocode Flowchart
  41. 41. C Programming - Lecture 1 41 4-Hierarchy Chart
  42. 42. C Programming - Lecture 1 42 4-Hierarchy Chart? • Shows the overall program’s structure. • Describes what each part, or Module, of the program does. • Also how each module relates to other modules in the program. • Main benefit: Provide help in the initial planning of a program.
  43. 43. C Programming - Lecture 1 43 Example of Hierarchy Chart Making of Tea 1-Boil Water 2-Boil Milk 3-Mix A & B Add Tea Powder Add Sugar “A” Wait for 3 Minutes “B” Mix Sugar + Boil Milk Tea is Ready
  44. 44. C Programming - Lecture 1 44 Class Problem Problem: calculate and report the grade-point average for a class
  45. 45. C Programming - Lecture 1 45 General Steps • Problem: calculate and report the grade-point average for a class • Discussion: the average grade equals the sum of all grades divided by the number of students • Output: Average grade • Input: Student grades • Processing: Find the sum of the grades; count the number of students; calculate average
  46. 46. C Programming - Lecture 1 46 Flowchart: Determine the Average Grade Ex: Three grades: 50, 75, 100 Start counter = 0; sum = 0 Get grade 50 counter = 1; sum = 50 Get grade 75 counter = 2; sum = 125 Get grade 100 counter = 3; sum = 225 No more data Average = 225 / 3 = 75 Display 75 End
  47. 47. C Programming - Lecture 1 47 Pseudocode: Determine the Average Grade • Determine the average grade of a class: Start SET counter to zero SET sum to zero IF there are more data (grades) – READ the next grade – INCREMENT the counter by 1 – ADD the grade to the sum ELSE – COMPUTE average = sum / counter DISPLAY average End
  48. 48. C Programming - Lecture 1 48 Another Example of Hierarchy Chart:
  49. 49. C Programming - Lecture 1 49

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