CSCI 125

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CSCI 125 161 / ENGR 144 Lecture 6

• Martin van Bommel

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Automatic Type Conversion

• Value of one type converted to another type as
  implicit part of computation
• 2 3.5 is 5.5
• Integer 2 is converted into float 2.0
• Assume variable total is of type double
• total 0
• Integer 0 converted to double 0.0

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Truncation

• Automatic type conversion of double to integer
  drops any decimal fraction
• Assume variable n is of type int
• n 1.99
• Result is value of n is set to 1

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Example of Truncation

• Write a program to convert a given number of
  centimeters to the equivalent in feet and inches
• Program cmtofeet.cpp

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Explicit Type Conversion

• Type cast - unary operator to convert value
• Desired type in parenthesis before value
• e.g. average sum / count
• If sum and count are integers, would perform
  integer division for average average (double)
  sum / count

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Shorthand Assignment

• Can replace variable variable op expression
• by variable op expression
• e.g. sum value counter 1 value /
  10

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Incrementing and Decrementing

• Further shorthands for
• incrementing - adding 1 to a variable variable
  
• decrementing - subtracting 1 from
  variable variable--
• e.g. counter

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Output

• cout used to display integers, real numbers
  (floats and doubles), characters, and strings
• cout ltlt exp1 ltlt exp2
• cout ltlt Measurement is
• cout ltlt (inches / 12) ltlt ft
• cout ltlt (inches 12) ltlt in

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I/O Manipulation

• ltiomanipgt has parameterized manipulators to
  modify behavior of cout
• Format cout ltlt manipulator(parameter)
• Examples
• setw sets minimum field width for value
• setprecision sets number of significant digits
• cout ltlt setw(5) ltlt setprecision(2) ltlt 1.53
• outputs 1.5

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ltiomanipgt

• May wish for setprecision to specify number of
  digits after decimal
• Can use the manipulator fixed
• cout ltlt setprecision(2) ltlt fixed

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Manipulators

• Flag Usage
• fixed fixed-point notation
• scientific scientific notation
• showpoint show decimal (even if .0)
• left left-adjust output
• right right-adjust output
• setw(n) width of print field
• setprecision(n) number of digits

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Formatted Output

• Need to align numbers in columns
• Name Number Salary Joe 123
  94.56 Joan 2340 125.38
• cout ltlt setprecision(2) ltlt fixed
• cout ltlt setw(8) ltlt left ltlt name ltlt right
• cout ltlt setw(4) ltlt num ltlt setw(8) ltlt salary ltlt
  endl