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# Spf Chapter5 Conditional Logics

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> Condition and operands
> if .. else if … else
> switch

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### Spf Chapter5 Conditional Logics

1. 1. Chapter 5<br />C# .NET: ConditionalLogic<br />is condition true?<br />false<br />true<br />Processing1<br />Processing2<br />
2. 2. Condition logic / Decisions and Branching<br />Recall the problems we solved in week #1 & 2: we used “if (n1 > n2) { … }” to check condition and branch<br />This chapter will cover condition logic in detail<br />
3. 3. General view<br />if (condition)<br />{ // condition is true <br /> // processing1<br />} <br />else <br />{ // condition is false<br /> // processing2<br />}<br />is condition true?<br />false<br />true<br />Processing1<br />Processing2<br />
4. 4. Condition<br />if (condition)<br />{<br /> // processing1<br />} <br />else <br />{<br /> // processing2<br />}<br />- The result must be ‘true’ or ‘false’<br /><ul><li> Cannot use ‘0’ or ‘1’
5. 5. Eg: For the condition (n1 > n2)</li></ul> => Is n1 greater than n2? <br /> The result is a ‘true’ or ‘false’<br />
6. 6. Condition<br />if (condition)<br />{<br /> // processing1<br />} <br />else <br />{<br /> // processing2<br />}<br />How to set condition?<br />Use operand to compare<br />Eg (n1 == n2)<br /> (n1 != n2)<br />
7. 7. Condition<br />if (condition)<br />{<br /> // processing1<br />} <br />else <br />{<br /> // processing2<br />}<br />With more than 1 condition<br />Use && for “and”:<br />(condition1) && (condition2)<br />Use || for “or”:<br />(condition1) || (condition2)<br />Eg (n1 >= 0) && (n2 >=0)<br /> => both n1 and n2 must be positive<br />Eg (n1 >= 0) || (n2 >=0)<br /> => either n1 or n2 is positive<br />
8. 8. condition<br />Comparing Boolean type:<br />boolbuttonClicked = false;<br />if (buttonClicked == true) { … }<br />if ( !buttonClicked) { … } // not buttonClicked<br />
9. 9. condition<br />Comparing Char type:<br />char answer = 'N';<br />if (answer == 'Y') { … }<br />
10. 10. condition<br />Comparing String type:<br />string input = ""; // empty string<br />if (input == "exit") { … }<br />
11. 11. condition<br />Comparing String type:<br />string input = ""; // empty string<br />if (input == "exit") { … }<br />String class has methods to do more complex checking such as Compare(), CompareTo(), StartsWith(), EndsWith(), Equals(), etc. Will cover some in Chapter 9<br /><ul><li>Good tutorial on C# string compare: </li></ul> http://alturl.com/tbwi<br />
12. 12. Other branching – if only<br />if (condition)<br />{ // condition is true <br /> // processing1<br />} <br />// No else branch<br />is condition true?<br />false<br />true<br />Processing1<br />
13. 13. Other branching – if .. Else if .. else<br />is condition1 true?<br />if (condition1)<br />{ // condition is true <br /> // processing1<br />} <br />else if (condition2)<br />{ // condition1 is false and <br /> // condition2 is true<br /> // processing2<br />}<br />else<br />{// condition1 is false and <br />//condition2 is false<br />// processing3<br />}<br />false<br />true<br />is condition2 true?<br />Processing1<br />false<br />true<br />Processing2<br />Processing3<br />
14. 14. Other branching - switch<br />switch (n1)<br />{<br /> case 1:<br /> // processing1<br /> break;<br /> case 2:<br /> // processing2<br /> break;<br /> default:<br /> // processing3<br /> break;<br />}<br />n1<br />1<br />2<br />3<br />Processing2<br />Processing3<br />Processing1<br />
15. 15. Other branching - switch<br />switch (n1)<br />{<br /> case 1:<br /> case 2:<br /> // processing2<br /> break;<br /> default:<br /> // processing3<br /> break;<br />}<br />n1<br />1, 2<br />3<br />Processing2<br />Processing3<br />
16. 16. Other branching - switch<br />switch (n1)<br />{<br /> case 1:<br /> // processing1<br />goto case 2;<br /> case 2:<br /> // processing2<br /> break;<br /> default:<br /> // processing3<br /> break;<br />}<br />n1<br />1<br />2<br />3<br />Processing1<br />Processing2<br />Processing3<br />
17. 17. Exercise 5.1<br />Textbook from page 93 – 98:<br />Part 1 if Statements <br />Part 2 else ... if in C# .NET <br />
18. 18. Exercise 5.2<br />Textbook from page 98 – 106:<br />Part 3 switch Statements in C# .NET <br />Part 4 C# Operators <br />
19. 19. Exercise 5.3(a)<br />For the GUI created in Exercise 3.2:<br />Rename all the controls to follow proper naming convention: egtextboxOutput, buttonZero, etc<br />Use winword to draft the pseudo codes for all the button click methods (you may need some variables outside the methods to be accessible by all methods)<br />
20. 20. Exercise 5.3(b)<br />For the GUI created in Exercise 3.2:<br />Create a new project: Exercise53B<br />Select all the controls in Exercise32 and paste into this new project<br />Code and debug manually by viewing the codes <br />No worry: we shall use debugging tool to debug this project in chapter 6: Debugging<br />
21. 21. Summary<br />Condition and operands<br />if .. else if … else<br />switch<br />