Your SlideShare is downloading. ×
  • Like
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.


Now you can save presentations on your phone or tablet

Available for both IPhone and Android

Text the download link to your phone

Standard text messaging rates apply

pre testing and post testing loops C++

pre testing and post testing loops C++

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
  • nice !!
    Are you sure you want to
    Your message goes here
No Downloads


Total Views
On SlideShare
From Embeds
Number of Embeds



Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

    No notes for slide


  • 1. Repetition (Looping Concept)
  • 2. After studying this chapter you will be able to: O BJECTIVES  Understand the basic components of a loop: initialization, control expression, and update.  Understand and use pretest, post-test, and count-controlled loops.  Differentiate between event-controlled and counter-controlled loops.  Write loops in C++ using while , for , and do...while loops.  Understand the limitations and use of break and continue statements in loops.
  • 3. Concept of a Loop
  • 4.
    • The two most important features of a computer are:
      • The ability to compare values to make decisions, and
      • The ability to repeat a series of operations in a controlled way.
  • 5. Figure : The concept of a loop
  • 6. Pretest and Post-Test Loops
  • 7.
    • Loops need to be coded in such a way as that they may be ended in a controlled manner.
    • The decision making process make take place at either the ‘ top ’ of the loop or at the ‘ bottom ’.
    • When the test takes place at the top of the loop, it is referred to as a ‘Pretest Loop’.
    • When the test takes place at the bottom of the loop, it is then a ‘Post-test Loop’.
  • 8. Pretest Loop In each iteration, the loop control expression is tested first. If it is true, the loop action(s) is executed; if it is false, the loop is terminated. Post-test Loop In each iteration, the loop action(s) are executed. Next, the loop control expression is tested. If it is true, a new iteration is started; otherwise, the loop terminates. Note:
  • 9. Figure : Pretest and post-test loops “ WHILE” test at the top…. “WHILE” test at the bottom CONDITION CONDITION
  • 10. Figure : Two different strategies for starting exercise CONDITION CONDITION False True
  • 11. Figure : Minimum number of iterations in two loops It is important that you understand this critical difference between the two basic types…
  • 12. Initialization and Updating
  • 13. Figure : Loop initialization and updating The initialization may optionally be part of the loop structure.
  • 14. Figure : Initialization and updating for exercise
  • 15. Event-Controlled and Counter-Controlled Loops
  • 16. Figure : Event-controlled loop concept
  • 17. Figure : Counter-controlled loop concept
  • 18. Loops in C++
  • 19. Figure : C++ loop constructs
    • All three C/C++ loop constructs involve a test.
    • The only difference is when the test occurs – either before or after doing something..
  • 20. Figure : The while statement while the expression is true, do …..
  • 21. Figure : Compound while statement
  • 22. Figure : for statement The for is just a special case of a while loop.
  • 23. The for loop is constructed in this way… for ( initialization statement(s) , while test expression , update statement(s) )‏ { body of loop… }
  • 24. A for loop is used when your loop is to be executed a known number of times. You can do the same thing with a while loop, but the for loop is easier to read and more natural for counting loops. Note:
  • 25. Figure : Compound for statement
  • 26. Figure : Comparing for and while loops
  • 27. In C/C++ the for loop counter is almost always initialized to a ZERO . So, if you want to do something 5 times, the for loop would be coded like this… for (int i = 0; i < 5; i++)‏ { do something… } It is also legal to have the test expression limit be a variable, as in: for (int i = 0; i < Num; i++)‏
  • 28. Figure : Format of the do…while statement
  • 29. Pre-test and post-test loops
  • 30. Assignment
    • Write a program (WAP) in C++ to accept a number and print its table upto 10 terms.
    • WAP in C++ to print the following output using for loops:
    • 1
    • 22
    • 333
    • 4444
    • WAP in C++ to accept a number and calculate its factorial.
    • eg. If number = 5
    • Factorial of 5 = 120 should be displayed
  • 31. The End