COMP102 LAB 2

1
COMP102 LAB 2
2
Division (/ and )

• Review
• 7 / 2 3.5 or 31
• 3 is the quotient and 1 is the remainder
• In C, quotient and remainder could be obtained
  from / an operators
• int quotient 7 / 2 // quotient 3
• int remainder 7 2 // remainder 1
• REMEMBER / operator performs differently on
  integers and non-integers
• int/int gt int
• double/double , int/double , double/int gt double

3
Random Functions

• Initialization
• Computers will always give the same output for
  the same inputs
• Different output requires different inputs!
• Time will usually be changed at different
  executions
• It is used as an input parameter to initialize
  the random number generator
• srand(time(0)) // need ltstdlib.hgt and
• // lttime.hgt

4
Random Functions (Cont)

• Generation
• rand()
• Generate a number between 0-RAND_MAX (32767 in
  VC)
• How to generate a different range, say 50-100?
• operator will return a number smaller than the
  divisor (i.e. x y gt between 0 and y -1)
• operator will give an offset to the generated
  number
• General solution (rand() num_possible_values)
  offset
• How to choose num_possible_values and offset?

5
Truncation and Rounding

• double-to-int conversion is usually done by
  truncation, i.e. extract the integral part from a
  real number
• In this lab, the total amount is rounded so that
• Total is rounded up if its fractional part gt0.5
• Total is rounded down if its fractional part lt
  0.5
• Can be done without if-statements
• Hints How truncation is done? (rounding up if
  its fractional part gt???, rounding down if its
  fractional part lt ???)

6
Fruits to be Charged

• Collect number of fruits to be purchased from
  user
• There are buy x get 1 free for different fruits
• You need to compute the actual number of fruits
  to be charged
• Hints , -, , /, operators are good enough!