cs110 lec 5

• Named constant

  A location in memory that we can refer to by an identifier, and in which a data value that cannot be changed is stored
• Named constants

  • const string STARS = "****"
  • const float NORMAL_TEMP = 37.0
  • const char BLANK = ' '
  • const int VOTING_AGE = 18
  • const float MAX_HOURS = 40.0
• Activity: Variables or Constants?

  • Pi
  • Coefficient of Friction of a Material
  • Number of power plants in Saskatchewan
  • Viscosity of a fluid
  • Days in a Week
  • Sales tax rate in Saskatchewan
  • Sales tax rate in Saskatchewan over the last 100 years
• Where do declarations go (for now)?

  1. #include <iostream>

  2. using namespace std;

  3. // constants go here

  4. const float PI = 3.14159;

  5. int main()

  6. {

  7. // variables go here

  8. int age;

  9. char gender;

  10. return 0;

  11. }
• Special Characters

  • #
  • <>
  • ()
  • []
  • {}
  • <<
  • ><
  • \\
  • "
  • ;
• Common Error 1: Missing Braces
• Common Error 2: Missing Semicolons
• Common Error 3: Missing Quotation Marks
• Common Error 4: Misspelling Identifiers
• Literals

  Numeric values that are directly included in the code
• Expression

  A valid arrangement of variables, constants, and operators that can be evaluated to compute a value
• Assignment statements with expressions

  First, the expression (right) is evaluated, then the resulting value is stored in the memory location of the variable (left)
• Data Types

  • boolean
  • char
  • int
  • float
  • double
• Characters & Strings in C++

  A character is any character in the ASCII data set. A string is a sequence of characters enclosed in double quotes.
• The sizeof function can be used to find the size (in memory) of a type
• Numerical Data Types


  • short int
  • long int
  • long long int
  • long double
• Floating point numbers


  Stored according to the IEEE 754 standard, using something like scientific notation with a sign, exponent, and mantissa
• Doubles are more precise than floats
• Signed vs. Unsigned int

  Unsigned numeric datatypes range from 0 to m, signed numeric datatypes range from -n to +(n-1)
• Many datatypes have synonyms you can use
• Overflow is unpredictable and can cause unexpected results
• Numeric Operators


  • =
  • +
  • -
  • *
  • /
  • %
  • pow(a, b)
• Example 1: Computing the Area of a Circle

  1. Read in radius

  2. Compute area

  3. Display the area