Correction of the Handout

1
Correction of the Handout

• include ltiostreamgt //Preprocessor
• using namespace std
• int main ()
• ..
• return 0
• A namespace is a named group of definitions. When
  objects that are defined within a namespace are
  used outside of that namespace, either their
  names must be prefixed with the name of the
  namespace or they must be in a block that is
  preceded by a using namespace statement.
  Namespaces make it possible for a program to use
  different objects with the same name, just as
  different people can have the same name. The cout
  object is defined within a namespace named std
  (for standard) in the ltiostreamgt header file.
• Throughout the rest of this class, every program
  is assumed to begin with the two lines
• include ltiostreamgt
• using namespace std

2
Week 3

• In this class, you will learn about
• Program Structure, Actions and Data Types
• Data Type Variables
• Output and Input action function coutltlt cingtgt
• Assignment
• Simple calculations
• Reference Programming with C, Theory and
  Problems of, Second Edition John R Hubbard
  (McGraw Hill, 2000, Schaum's Outline Series)

3
Data Type Variables

• Variables
• Name of a variable
• A variable has a name, which is given by the
  programmer by declaration or definition. When the
  name is given, the memory for it is specified.
• Rules for creating names of variables
• Rule 1 a name starts with a letter.
• Rule 2 a name is unique, which should be
  different from other words in the program.
• Rule 3 names are sensitive to letters upper case
  or lower case.
• Doug is not equivalent to doug.
• Rule 4 names should be meaningful.

4
Data Type Variables

• For example, int alice
• name of variable alice
• type int(eger)
• tail

Using namespace std
5
Data Types
6
Part of Integral Type
7
Float type example

• It shows that the 32 bits it uses to store a
  float are partitioned into 3 parts 23 bits for
  the mantissa, 8 bits for the exponent, and 1 bit
  for the sign. The 23-bit mantissa produces a
  floating-point value with 6 significant digits,
  and the 8-bit exponent yields a range in
  magnitude from about 1037 to about 3 1038.
  i.e., 0.0000000000000000000000000000000000001 lt
  x lt 300,000,000,000,000,000,000,000,000,000,000,
  000,000 for any variable x declared to have type
  float.

8
A new variable char (character data)

• Definition
• A char variable is defined to hold a single
  character that appears on the keyboard.
• Difference between a char and a string is that a
  char is a single character while a string is a
  collection of serial characters.
• Declaration
• char c
• Input a char variable from keyboard
• A space cannot be input from keyboard

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A new variable char (character data)
10
A new variable char (character data)
11
Output action function coutltlt

• More actions by using a back slash \
• The sign \ is not a normal character but a
  control character to instruct the computer to
  take an action corresponding to next character.
  See table below,
• Escape characterEffect\nNewline\tHorizontal
  tab\rCarriage return\bBackspace\aBell or
  beep\\Backslash\Double quote\Single
  quote\?Question mark

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Input action input function cingtgtAssignment

• We have seen that one way of assigning a variable
  with a value is to input a number of digits on
  keyboard. Another important way is to use an
  assignment statement. For example
  (assignment1.cpp),

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Simple calculations
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Simple calculations
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Integer Calculation Example

• int main()
• // tests operators ,-,,/,and
• int m54
• int n20
• cout ltlt "m " ltlt m ltlt " and n " ltlt n ltlt endl
• cout ltlt "mn " ltlt mn ltlt endl // 5420 74
• cout ltlt "m-n " ltlt m-n ltlt endl // 54-20 34
• cout ltlt "mn " ltlt mn ltlt endl // 5420 1080
• cout ltlt "m/n " ltlt m/n ltlt endl // 54/20 2
• cout ltlt "mn " ltlt mn ltlt endl // 5420 14
• Return 0

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Prefix and postfix increment

• Examplek x//prefix increment
• is equivalent to
• x x 1 //increment n first
• k x//assign xs value to k
• Examplek x//postfix increment
• is equivalent to
• k x//assign xs value to k
• x x 1//and then increment x

17
Applying the Pre-increment and Post-increment
Operators

• int main()
• // shows the difference between m and m
• int m,n
• m 44
• n m // the pre-increment operator is applied
  to m
• cout ltlt "m " ltlt m ltlt ", n " ltlt n ltlt endl
• m 44
• n m // the post-increment operator is
  applied to m
• cout ltlt "m " ltlt m ltlt ", n " ltlt n ltlt endl

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COMPOSITE ASSIGNMENT OPERATORS

• The standard assignment operator in C is the
  equals sign . In addition to this operator, C
  also includes the following composite assignment
  operators , -, , /, and .
• When applied to a variable on the left, each
  applies the indicated arithmetic operation to it
  using the value of the expression on the right.

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Applying Composite Arithmetic Assignment Operators

• int main()
• // tests arithmetic assignment operators
• int n22
• cout ltlt "n " ltlt n ltlt endl
• n 9 // adds 9 to n
• cout ltlt "After n 9, n " ltlt n ltlt endl
• n - 5 // subtracts 5 from n
• cout ltlt "After n - 5, n " ltlt n ltlt endl
• n 2 // multiplies n by 3
• cout ltlt "After n 2, n " ltlt n ltlt endl
• n / 3 // divides n by 9
• cout ltlt "After n / 3, n " ltlt n ltlt endl
• n 7 // reduces n to the remainder from
  dividing by 7
• cout ltlt "After n 7, n " ltlt n ltlt endl