CIS 199 Test 01 Review. Computer Hardware Central Processing Unit (CPU) Brains Operations...
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Transcript of CIS 199 Test 01 Review. Computer Hardware Central Processing Unit (CPU) Brains Operations...
CIS 199 Test 01 Review
Computer Hardware Central Processing Unit (CPU)
Brains Operations performed here
Main Memory (RAM) Scratchpad Work area for programs, process, temporary data
Secondary Storage Hard drive Flash drive CD, DVD
Input, Output Devices Input
Takes data IN Keyboard, Mouse, Game Controller, Microphone
Output Pushes, places data OUT Display, Speakers, Printers
Programs and Digital Data Programs
Operating Systems. Microsoft Office, Web browsers Instructions read by CPU and processed
Digital Data 1’s 0’s …forms binary (base 2)
Built-In Types
Properties Exposed “Variables” or accessible values of an object Can have access controlled via scope modifiers When thinking of properties: Values and definitions “get” – Code to run before returning a value “set” – Code to run before updating a value
Can be used for validation and other processing actions “value” is a keyword in “set”
Methods Actions, code to be executed May return a value, may take value (not required) Can be controlled via scope keywords Can be static
Scope “private” – Can only be accessed by the class, object itself “protected” – Can only be accessed by the class, object, or
any child classes, objects “public” – Available access for all
Named Constants AVOID MAGIC NUMBERS! Allows for reference across similar scope Change once, changes everywhere
Conditional Logic if(expression)
If ‘expression’ is true If not true, skipped
else if(expression) Can be used to ‘chain’
conditions Code runs if ‘expression’ is
true else
Code to execute if ‘expression’ false
Statements can be nested
Relational Operators >
Greater than <
Less than >=
Greater than OR equal to <=
Less than OR equal to ==
Equal to !=
NOT equal to
X > Y
X >= Y
X < Y
X <= Y
X == Y
X != Y
Operator Precedence (Highest) ++, --, ! * / % + - < > <= >= == != && || = *= /= %= += -= (Lowest)
Detailed from:http://msdn.microsoft.com/en-us/library/2bxt6kc4%28v=vs.100%29.aspx
Comparing Strings You can use
==, !=
You cannot use >, >=, <, <=
You SHOULD use: String.Compare(s1, s2)
s1 > s2 Returns positive Number
s1 = s2 Returns zero
s1 < s2 Returns negative number
Compares the unicode value of EACH character
Exceptions andException Handling Exceptions are…
“Exceptional” events Unexpected events, errors during runtime Unhandled exceptions? Stack trace and application death
Handled with try/catch/finally blocks Try block “attempts” to run the code in question Catch block handles the exception(s) that may occur Finally block, optional, always executes
Sample Questions
What does ‘WYSIWYG’ stand for? What You See Is What You Get
What is the difference between a high-level and a low-level language? Low-Level
Little to no ‘abstraction’ from the hardware or computer “Close to the hardware” Simple, but Difficult to use Machine code, assembly, C (in some cases)
High-Level Very strong ‘abstraction’ from the hardware or computer “Far from the hardware” Easier to use, abstraction adds complexity C++, Java, C#, Python
How is the lifetime of a FIELD different from a lifetime of LOCAL variable? Fields are members of their
containing type Fields can be used
everywhere with appropriate scope
Local variables can be used only in their “local” environment
What two things does a variable declaration specify about a variable? Type Identifier
TYPE IDENTIFIER
Describe ‘&&’ and ‘||’ and how they work. && (AND)
Returns true if conditions are ALL true
“If you do well on the test AND the quiz, you will earn a great grade!”
|| (OR) Returns true if ANY
conditions are true “You can run a mile OR
walk two miles (possible do both!)”
Why is ‘TryParse’ more effective than ‘Parse’?
Less code No try / catch required
What is the difference between a SIGNED an UNSIGNED int?
What is the difference between syntax errors and logic errors? Syntax Errors – Errors that prevent compilation or other
factors that prevent successful compilation striing myString = string.Empty; // Won’t compile, syntax error
Logic Errors – Errors that occur during runtime, such as incorrect comparison or other unexpected behavior If(grade > 60) { Code if grade is F } // Incorrect operator used
What are the “Five logical units”? CPU – Processing, instructions Memory – Scratch pad, working space (Temporary) Secondary Storage – Hard drives, storage (Long term) Input – Keyboards, Mice, Controllers Output – Monitors, Speakers, Printers
Explicit type conversion? Why and how? Variables must be used for a single type never change Move from one type to another, must cast EXPLICIT cast / type conversion
Aware of information loss
Write a code fragment that will display “Good Job” when int variable score is 80 or more, “OK” when score is 70 – 79, and “Needs Work” for any score under 70.
Write a code fragment that will apply a 10% discount to the value in double variable total when int variable numItems is 5 or more and int variable zone is 1, 3 or 5.
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