1D04 Final Summary.pdf

7 Pages
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Department
Engineering (General)
Course Code
ENGINEER 1D04
Professor
Spencer Smith

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Description
TOPICS 1. Computing. • What computing is. ◦ Computing is the development and use of the computer hardware and software to: ▪ Solve problems. Create smart products. Explore our world. Connect people. ◦ Computing is a mixture of: ▪ Science, Engineering, Mathematics, and Design. • Main branches of computing. ◦ Computer Science. Software Engineering. Information Technology. • Why engineers need to study computing. ◦ Computing is used everywhere in today's world. ◦ Software-based tools can enhance the capabilities of engineers. ◦ Software can increase the effectiveness of the products engineers design. ◦ Solid understanding of computing is a crucial component of being a competent and ethical engineer. ◦ Computing contains lots of engineering ideas. 2. Mathematical Concepts. • Number systems. • Sequences (finite and infinite). • Σ and Π notation. • Functions. • Boolean operators and truth tables. 3. Programming Languages. • Values and types. ◦ Values are the data stored and manipulated by the computer programs. ◦ Types is a syntactic entity that denotes a collection of values of similar form. • Expressions. ◦ Asyntactic entity that denotes a value. ◦ Avalue will always be a result of an expression. • Variables and constants. ◦ Variables: ▪ The exact definition of a variable varies across disciplines and contexts. ▪ In Python, a variable is a name bound to a value. ◦ Constants: ▪ Python built-in constants includes True and False. ▪ Convention dictate user-defined constant to be written in all capitals. ▪ Python allows changing of constant without restrictions. • Statements. ◦ Is a syntactic entity that states something to be done. ◦ Statement DOES something (like assigning a value to a variable). • Representation of number systems. ◦ Review on how to convert to base 10 decimals. ◦ Review on how to convert base 10 decimals to another base. • Characters and strings. ◦ Characters: ▪ In computing, character represent graphemes (the unit of a writing system). ▪ ASCII: • Based on English alphabets. Contains 128 characters represented by character of 7 or 8 bits. ▪ Unicode: • Represent the graphemes of world major writing system. • Characters represented by 8, 16, 32 bits. ◦ Strings: ▪ Is a finite sequence of characters. • Function definition and application. ◦ Functions are subprogram that: ▪ Are defined and applied by the developer. ▪ Reduce code duplication. ▪ Improve software quality (maintainability, understandability, reusability). ◦ Evaluation steps for a function: ▪ Calling program is suspended. ▪ Values of formal parameter are bound to the values of actual parameter. ▪ Body of the function is executed. ▪ Output value of the function is returned to the calling program. ▪ Calling program execution is resumed just after the function was called. ◦ Side-effect ▪ Python passes parameter by value. If the value being passed is a mutable object, then changes made to the object may be visible to the caller. ▪ Aliasing problem in a object is an example of side-effect. ▪ Basically, any changes made by the function NOT through the return method is a side-effect. ▪ Note that changes includes modifying the display. Like printing a data using print x instead of using return x. ▪ Aproper function makes no changes in the environment. It receives arguments, computes a value, and returns it. Anything else is a side effect. • Name spaces and scope. ◦ Namespace ▪ is a space that holds a bunch of names ▪ each namespace is isolated (per module, function, etc) ◦ Scope ▪ is a region of program where a namespace is accessible ▪ the scope in which a name is declared determines what namespace the name is in ▪ scope are nested ▪ normally a variable created outside of the innermost scope is read-only within the innermost scope • Modes of execution. Python supports all three of these modes. ◦ Interpreted: ▪ Running the code line by line. ▪ Supports interactive development and debugging of code. ▪ Slower than executing compiled code. ◦ Compiled into byte code: ▪ Programs are more portable. ▪ Byte code is slower than native code. ▪ Python's byte code end with *.pyc. ◦ Compiled into native machine code: ▪ The machine code is optimized to run fast. ▪ Code development is more difficult. • Programming paradigms. ◦ Programming paradigms is a well-developed style of programming. ◦ Chief programming paradigms: ▪ Imperative – Program statements modify a program's state. ▪ Object-oriented – Data and operations are organized into units called objects. ▪ Functional – Functions are first-class values and function applications are side-effect free. ▪ Logical –Answers to questions are deduced from logical statements. ◦ Python supports all these paradigms except logical. 4. Values, Types,And Expressions In Python. • Numeric types. ◦ Int: ▪ 32-bit machine integers. +ve or -ve whole numbers. ▪ Integer divisions is a pitfall to watch out for. ◦ Long: ▪ Used to store integer of arbitrary size. ◦ Float: ▪ 64-bit floating point fractional numbers. ▪ Can be shown in scientific notation. ▪ Floats can only stored approximations to real numbers. • Thus avoid testing x == y or x != y when x and y are floats. ▪ Floats are fixed digits that has no relation to memory. • Sequence types. ◦ String is immutable finite sequence of characters. ◦ List is mutable finite sequence of values (the values can have different types). • Objects. ◦ Data ▪ Field – define the object's state, which is the set of information that is stored in the object. ◦ Operations ▪ Methods – define the object's behaviour. • Accestor (aka selector or getter) – is a method that retrieves information about the state of an object. • Mutator (aka setter) – is a method that modifies the state of an object. ◦ Aliasing Problem ▪ In Python, aliasing consist of the same jar model.As in, the same data can be called and changed by different variables. ▪ This is only a problem with mutable object (which string is not). • Booleans and boolean operators. ◦ Logical Operator ▪ NOT > AND > OR ◦ Boolean Properties ▪ Anything ORED with True is just True. • a or true == true ▪ Both AND and OR distribute over each other. • a or (b and c) == (a or b) and (a or c) • a and (b or c) == (a and b) or (a and c) ▪ Double negative cancels out. • not(not a) == a ▪ De Morgan's Laws: • not(a or b) == (not a) and (not b) • not(a and b) == (not a) or (not b) ◦ Implicit Type Conversion ▪ Values of built-in non boolean types are implicitly converted to boolean values when they are used as booleans. ▪ Empty values equals False. ◦ Short-Circuit ▪ Used forAND and OR. ▪ Is an evaluation process that returns an answer as soon as the result is known without evaluating all of its sub-expressions. • “cat” and “dog” gives “dog” since “cat” returns True • “cat” or “dog” gives “cat” since “cat” returns True • if x = 3 then x == x and x + 4 gives 7 when evaluated • Exceptions. ◦ Raise statement ◦ Try-except statement ▪ Try-except is capable of catching multiple type of errors but not all at once. • Type conversion. ◦ Type error ▪ Occurs when one type is used where another type is expected. ▪ Types are used to catch type errors at run-time. ◦ Python will automatically converts values in mixed type numeric expressions to resolve type conflicts. The value of the “narrower” type will be converted to the “wider” type. ▪ Eg: 2/3.4 is converted to 2.0/3.4. 5. Statements In Python. • Assignment statements. ◦ Used to assigned a identifiers to a value. ◦ Identifiers begin with underscore or letter. Followed by a combo of: letter, digit, underscore. Identifiers are case sensitive. • Conditional statements. ◦ Selects a statement for execution on the basis of whether a condition represented as a Boolean expression evaluates to True or False. ◦ Different kind of conditional statements includes: if, if-else, if-elif-else, try-except, and while statements. • Definite loops. For loop. ◦ Can be made into indefinite loop under certain events. • Indefinite loops. While loop. Can be broken using break. ◦ Interactive loops. ◦ Sentinel loop (until a sentinel value is met). ◦ File reading loop (until end of file). ◦ Repeat-until loop (until a condition is met). ◦ Infinite loop. • Function definitions. ◦ >>> def function_name(formal_parameter): ◦ >>> return value ▪ Used to obtain a result of the function. ▪ Function will always return a value even if return is not used. When return is not used, function will return a special object NONE. ▪ If multiple values are return, then a special type tuple is returned. • Tuple: ◦ Has round brackets. ◦ Are immutable. ◦ Can be accessed using index notation. • Exception handling. ◦ >>> try: ◦ >>> statements ◦ >>> except Exception1: ◦ >>> exception_handler1 • Class definitions. ◦ >>> class class_name: ◦ >>> def __init__(self, formal_parameter): ▪ Is a special constructor for class. Its job is to create the class as a object. • Method definitions. ◦ Is a definition of a function within a class. Used the same syntax and involves the same properties of a regular functions. ◦ The only different is to access a method function within a class, one would need to use a do
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