CIS 199 Test 02 Review
Loops
 for
 “For a given value X, while X is true, modify X…”
 while
 “While X is true…”
 do – while
 “Do these tasks, while X is true…”
 foreach
 “For every X in this set of Y do the following…”
for Example
while Example
do while Example
foreach Example
Key Loop Details
 Loops are NOT guaranteed to execute at least once!
 …only exception is ‘do while’
 ‘for’ loops require a variable, condition, and ‘step’ instruction
 ‘while’, ‘do while’ loops require a boolean expression
 ‘foreach’ loops require a collection of items
 Arrays
 Lists
 Generic Collections
Files
 OpenFileDialog
 Used to load file from location
 SaveFileDialog
 Used to select file save location
 BOTH very User friendly!
OpenFileDialog
OpenFileDialog
SaveFileDialog
SaveFileDialog
Random Numbers in C#
 Provided from: System.Random
 Is ONLY pseudo-random
 Produces a finite set of values with equal probability
 Not truly random, follows a mathematical algorithm
 Created with OR without seed value
 Common methods used:


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Next()
Next(int)
Next(int, int)
NextDouble()
Creating and using a
Random Object
Usage & Expected Results
of Random Methods
Methods
 Actions, code to be executed
 May return a value, may take value (not required)
 Can be controlled via scope keywords
 Can be static
Methods &
Modularizing Your Code
 Methods
 Break out ‘steps’
 Easier to test
 Easier to visualize
Methods &
Modularizing Your Code
Example
Arrays
Arrays
Sample Questions from
Blackboard Wiki
The ‘switch’ statement can replace
nested if/else. But under what
conditions?
 When matching on a specific…




Value
Type
Enumeration
…other data
What does a ‘break’ statement do
in a loop?
 It stops (BREAKS) loop execution
 Code continues, no further loop iterations
What does a ‘continue’ statement
do in a loop?
 Goes to the next iteration
 CONTINUES loop execution, by skipping current iteration
What are preconditions and
postconditions for a method?
 PRECONDITIONS
 Conditions that MUST be TRUE before method execution
 POSTCONDITIONS
 Conditions that WILL be TRUE after method execution
What is the difference between a
void method and a value-returning
method?
 VOID Method
 Returns nothing!
 …a void return.
 Value-Returning
 Returns a value!
 …that’s not a void return.
Compare and contrast the use of
pass by value against pass by
reference, using key word ref
versus pass by reference using
keyword out.
 Pass by Value
 Passes a copy of the value
 Not the object itself
 Pass by Reference
 Passes the actual object itself
 ‘ref’
 Causes a pass by reference on a variable
 ‘out’
 Is used to reference a variable that the method will update
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