cis 199 test 02 review
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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:
Next() Next(int) Next(int, int) NextDouble()
Creating and using aRandom Object
Usage & Expected Resultsof 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 CodeExample
Arrays
Arrays
Sample Questions fromBlackboard 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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