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CSC115 Introduction to Computer Programming. Zhen Jiang Dept. of Computer Science West Chester University West Chester, PA 19383 zjiang@wcupa.edu. Table of Contents. Structure Selection (Decision) Loop Function Interesting features Graphics Other tools. Selection (Decision).
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CSC115 Introduction to Computer Programming Zhen Jiang Dept. of Computer Science West Chester University West Chester, PA 19383 zjiang@wcupa.edu
Table of Contents • Structure • Selection (Decision) • Loop • Function • Interesting features • Graphics • Other tools
Selection (Decision) • Price is right. • Sample execution (click on this link to try)
No Yes Condition Action 1 Action 2 Action 3
If block if condition then action 1 (statements 1) else action 2 (statements 2) end if action 3 (statement 3)
Condition • Simple condition • Format <Value> <relational operators> <Value> • Number value relational operators =, <>, <, >, <=, >= • String value relational operators =, <> • Complex condition • And, or, not • Truth table
Development Process • Identify two exclusive options • Implement each handling in different action parts • Identify the situation (values) for option selection • Make a condition so that all the situation value for option part 1 will lead to this condition true. • Verify all the situation value for option part 2 will lead to this condition false, otherwise, revise the above condition!
Multiple selection • Nested if block • Example: letter grade
Comments: • Nested if block for multiple section problem If then case 1 Else if then case 2 else … end if End if
Try 2 • Dim x as integer, y as integer • x = text1.text • y=0 • if x > 3 then • y =1 • if x >10 then • y = 2 • else • y = 3 • End if • End if • Listbox1.Items.Add( y ) • Dim x as integer, y as integer • x = text1.text • y=0 • if x > 3 then • y =1 • if x > 10 then • y = 2 • End if • else • y = 3 • End if • Listbox1.Items.Add( y )
Dim x as integer, y as integer • x = text1.text • y=0 • if x > 3 then • y =1 • if x >10 then • y = 2 • else • y = 3 • End if • End if • Listbox1.Items.Add( y ) • Dim x as integer, y as integer • x = text1.text • y=0 • if x > 3 then • y =1 • if x > 10 then • y = 2 • End if • else • y = 3 • End if • Listbox1.Items.Add( y )
Select block • Select case • A constant • A variable • An expression • Is • Range • Else • or case