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Announcements

Announcements. Quiz 1 Next Week. Built-In (or Primitive ) Data Types for Variables. int : Integer Range of Typically -32,768 to 32,767 (machine and compiler dependent) float : Real Number (i.e., integer part, decimal part, and exponent part) Range of Typically 10e-38 to 10e38

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Announcements

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  1. Announcements • Quiz 1 Next Week

  2. Built-In (or Primitive) Data Types for Variables • int: Integer Range of Typically -32,768 to 32,767 (machine and compiler dependent) • float: Real Number (i.e., integer part, decimal part, and exponent part) Range of Typically 10e-38 to 10e38 • double: Larger Real Number (10e-308 to 10e308) • char: Character

  3. Naming Variables in C++: Identifiers • Can Use Letters: Remember That C++ is Case Sensitive (e.g., NumWidgets Is Not the Same as numwidgets) • Can Use Digits 0-9, and Underscore • Cannot Start with a Digit • Cannot Contain Spaces or Other Characters • Typically Maximum of 32 Characters • Cannot Use C++ Keywords

  4. Naming Variables (Cont) • Should Use a Meaningful, Descriptive Name so that Variable’s Use Is Easily Understood: • Examples: counter, second, minute, length, width • Be Consistent with Case; Usually Lower Case with Upper Case for Second Part of Variable Name • Examples: averageRainfall, totalStudentGrades, maxBuildingHeight, minPackageWeight;

  5. Named Constants • Constant: An Identifier that Is Initialized to a Value that Cannot Change • Usually Declared at Top of Program using Keyword const • Standard Naming of Constants Is to Use All Upper Case Letter with or without Underscore between Words • All Constants Must Be Initialized • Syntax: const int MAXHT = 100;

  6. Advantages of Constants • Easier to Understand • Easier to Modify • Example: Compare using Number 5000 in Program versus Constant MAXHT

  7. Named Constants const int MAXHT = 100; main() { ... currentHeight > MAXHT ... bridgeHeight == MAXHT ... bridgeHeight + newAddition >= MAXHT ... // used MAXHT 223 times in this program }

  8. Literal Constants (Values) • Constants Whose values Are Already Known: Characters (Specified Inside Single Quotes): ‘A’ , ‘a’ , ’5’ , ’ ‘ , ’\n’ (newline) , ’\0’ (NULL Character) Integers: 10, 1345, -34 Float or Double: 2.3, -45.18, 10.6e6 String (Specified Inside Double Quotes): “HELLO” , “What a great deal.” , “5”

  9. Input and Output • Also Known as I/O • Output Stream: cout <<variable; • Input Stream: cin >> variable; • New Line: endl • All C++ Statements End in Semicolon (;)

  10. Input and Output Example #include <iostream> using namespace std; int main() { int numEntered; cout << “Please enter an integer:”; cin >> numEntered; cout << “Thanks, you entered: “ << numEntered << “.” << endl; }

  11. Characters and Strings • Standard Template Library (STL): Library of C++ Functions Used Worldwide • String Type NOT Built-in in C++ • String Type Defined in STL • To Use STL Strings: #include <iostream> #include <string> using namespace std; string lastName;

  12. STL Strings • Declaration: string yourName; • Assigning a Value to a String: yourName = “A. Goose”; • String Constants (Values) Must Be Enclosed in Double Quotes

  13. Input String Example #include <iostream> #include <string> using namespace std; int main() { string lastName; cout << “Enter your last name: “; cin >> lastName; cout << “Your last name is: “ << lastName << endl; return(0); }

  14. Expressions • Expression: A Sequence of One or More Identifiers and Operators that Evaluates to a Value • Operator: A Symbol Expressing a Way to Modify a Value or Values (e.g., + for Addition) • Operand: A Value Being Modified by an Operator • Example Expressions: 5 currentHeight currentHeight + 10

  15. Arithmetic Expressions • Standard Arithmetic Operations Can Be Performed: Addition, Subtraction, Multiplication, Division • Standard Arithmetic Operators Can Be Used for These Operations: +, -, *, / • Others: % - “Modulo (Mod)” – Remainder after Integer Division -- Decrement (Subtract 1) ++ Increment (Add 1)

  16. Order of Operations • Precedence: Level of Importance of Operations Multiplicative Operators Have Higher Precedence than Additive Operators: *, /, % Higher +, - Lower • Associativity: Order of Operation for Equal Level Precedence Most Operators Have Left-to-Right Associativity Use Parentheses to Force Differing Precedence of Operations

  17. Know for the Quiz • All Terms (Underlined Items) • Variable Declaration, Initialization, and Assignment • Constant Declaration • Expressions • Operators • Input (cin) and Output (cout) • Everything in Labs through Lab 2

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