C++ Exam 1 Study Guide: Unit Analysis, Exponential Notation, Software Development Phases, Study notes of Electrical and Electronics Engineering

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Michael Morrison Problem Solving With C++ 2/20/2011 Professor David McPherson Exam 1 Study Guide  Chapter 1 o Unit analysis  Making sure to use consistent and correct units when making computations  Cancel out corresponding units in the numerator and denominator  Use one conversion factor at a time, cancel as you go  If the final units are not correct, the numerical answer is also wrong  English Engineering system and SI units  1 BTU = 1055 J o Exponential (4.27e3) vs. Scientific (4.27 x 103) Notation  Use exponential to make entering numbers in a computer program easier  Use scientific notation when performing hand calculations for verification  Evaluating formulas that use very large or small numbers  10n x 10m = 10n+m  1/10-n = 10n  Pico, nano, micro, milli, kilo, mega, giga, tera o Phases of software development I. Development and design  Analysis (understand required outputs/inputs)  Design (develop a solution/algorithm)  Coding (actually write a C++ program that carries out the algorithm.) o Sequence – defines the order in which instructions are executed o Selection – allows a choice between different operations, based on some condition o Iteration – allows the same operation to be repeated based on some condition (a loop or repetition) o Invocation – involves invoking a set of statements when needed  Testing/correcting o Testing – verify correctness and that requirements are met o Bug – A program error o Debugging – the process of locating an error and correcting/verifying it o Testing may reveal errors, but does not guarantee the absence of errors. II. Documentation (essential for user and for maintenance)  Program description  Algorithm development and changes  Well-commented program listing  Sample test runs  Users’ manual III. Maintenance (The longest phase; possibly the primary source of revenue; good documentation is vital.) It includes:  Ongoing correction of newly discovered bugs  Revisions to meet changing user needs  Addition of new features o Algorithms  Step-by-step sequence of instructions  Must terminate  Describe how data is processed to produce the desired output  Pseudocode – English-like phrases used to describe the steps  Formula – mathematical equations  Flowchart – diagrams with symbols o Four ways to construct a program o “Programming Language” (a set of instructions used to construct a program)  Machine  Can actually be used to operate a computer  AKA executable programs, or executables  Consists of a sequence of binary instructions  Contains an instruction and an address  Assembly  Substitute word-like symbols, such as ADD, for binary opcodes  Use decimal numbers and labels for memory addresses  Assemblers – Translates programs into machine language  Low level  Tied directly to one type of computer (machine or assembly language)  High level  Instructions closer to real languages, like English  Can be run on a variety of computer types (like C++, Java, etc.)  Source code  Can be written in a high- or low-level language  Must be translated to machine instructions through either a… o Interpreter – each statement is translated individually and executed immediately after translation\ o Compiler – All statements are translated and stored as an executable program, or object program; execution comes later  About C++  Chapter 3 o Assignment statement  Left side is a variable (numberInput) = right side is a value (3.54)  End with a semicolon  You can use “+=” or “*=”, etc. to make something operate upon itself  Prefix increment operator “++i” adds one, then assigns  Postfix increment operator “i++” assigns, then adds one o Coercion – forcing a data value to another data type  Value of expression on right side of an assignment will be coerced to the data type of the variable on the left side  Variable on left side may also be used on the right side of an assignment o Formatting output  “setw(n)” sets a width of n  “setprecision(n)” sets the floating-point precision to n places (significant figures unless “fixed” is used – then it’s digits after the decimal place)  “fixed” forces a decimal point and default of six digits after it o Calling a function: include header file if necessary, then [function name](data passed to the function) o Symbolic constant – constant value that is declared with an identifier using the “const” keyword (a constant’s value cannot be changed)  Chapter 4 o An “if-else” statement implements a decision structure for two choices  A condition is evaluated to a numerical value, with a non-zero value considered to be true and a zero value to be considered false  Common problems:  Misunderstanding what an expression is  Using the assignment operator (=) instead of the relational operator (==)  An “if-else chain” is created by nesting “if-else” statements inside the “else” portion of the outer “if-else”  If any condition is true, the whole thing terminates  The final “else” is executed only if no conditions were true  This chain provides one selection from many possible alternatives o Relational expression – compares two operands or expressions  Uses relational operators (such as <, >, <=, >=, ==, or !=>)  evaluated to a numerical value of 1 or 0 (true or false)  “char” values are automatically coerced to “int” values for comparison  Strings with the first lower character is considered smaller o Logical operators – (&& is AND, || is OR, ! is NOT) o Compound statement – a sequence of single statements contained between braces  Creates a block of statements, which is legal anywhere that a single statement is legal  Any variable declared within a block is usable only within that block o Scope – the area within a program where a variable can be used (depends on where it was declared) o Switch statement – provides for one selection from many alternatives  “switch” keyword starts the statement, and is followed by an expression to be evaluated  “case” keyword identifies a value to be compared to the switch expression  When a match is found, that corresponding case block is executed  **All further cases after a match is found are executed unless a “break” statement is found.