CS304: Lecture 2

1
CS304 Lecture 2

• Basics of C Programming
• Deitel, Ch. 1-5
• http//www.cis.uab.edu/cs304

2
Outline

• Using Datatypes
• Integers
• Char
• Arithmetic Operations
• Relational Operators
• Global functions
• Class Overview
• Data Members
• Public vs. Private
• Member Functions
• Setters and Getters (Why?)
• Constructors
• Implicit vs. Declared
• Header Files
• Separating Interface and Implementation
• Control Structures
• If, if-else, conditional operator (?), while,
  do-while, for, switch

3
Ladies and Gentlemen, Start Your Compilers!

• include ltiostreamgt
• using stdcout //Whats up with that ?
• int main()
• cout ltlt "Hello, world!\n"
• return 0

4
Namespaces, a Conceptual View
namespace std //classes //functions //globals

namespace myspace //classes //functions //glo
bals
namespace oracle //classes //functions //glob
als
5
Ladies and Gentlemen, Start Your Compilers!

• include ltiostreamgt
• using stdcout
• int main()
• cout ltlt "Hello, world!\n"
• // Whats up with that ltlt?
• return 0

6
Streams and their Operators

• Several streams are already available
• cout Standard Output
• cin Standard Input
• cerr Standard Error
• Operators
• ltlt -- Put onto the stream
• gtgt -- Take off of the stream
• Put stuff onto cout, take stuff off of cin

7
Datatypes A Review

• Numbers int, float, double
• Qualifiers short or long, signed or unsigned
• Size in bytes (on the blazers)
• char 1 (What is a char, anyway?)
• short int 2
• int 4
• long int 4
• long long int 8 (dont try this at home)
• float 4
• double 8
• long double 16

8
A Silly Example

• include ltiostreamgt
• using namespace std
• int main()
• int a short int b long int c
• float d double e long double f
• char g
• cin gtgt a gtgt b gtgt c gtgt d gtgt e gtgt f gtgt g
• cout ltlt a ltlt b ltlt c ltlt d ltlt e ltlt f ltlt g
• return 0

9
Arithmetic and Relational Operations

• Arithmetic The standards , -, /, , , ()
• They work the way Java programmers expect
• Relational gt, gt, lt, lt, , !
• Same goes
• Thirty seconds, and I have already spent too much
  time on this!

10
Functions

• Functions can be a part of a class
• They can also be declared in a global scope
• Globals in this case arent necessarily a bad
  thing
• Ever seen someone declare a global class in
  java for misc. static functions?
• The interface can be declared before the function
  itself
• This is a good practice

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Another Example

• include ltiostreamgt
• using namespace std
• int mymin(int a, int b)
• int main()
• int a, b
• cout ltlt "Please enter two numbers "
• cin gtgt a gtgt b
• cout ltlt mymin(a, b)
• int mymin(int a, int b)
• if (a lt b) return a
• return b

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Classes in C

• Work a lot like in Java, with less typing!
• Not necessary to assign a new instance at
  declaration
• Treated more like a primitive datatype

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Class Example

• include ltiostreamgt
• include ltstringgt
• using namespace std
• class name
• public
• string firstname
• string lastname
• void printName() cout ltlt firstname ltlt " " ltlt
  lastname ltlt endl
• int main()
• name MyName
• MyName.firstname "Matthew"
• MyName.lastname "Curry"
• MyName.printName()
• return 0

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Another Example Functions, Getters, Setters

• include ltiostreamgt
• include ltstringgt
• using namespace std
• class name
• public
• void setfirstname(string firstname)
  this-gtfirstname firstname
• string getfirstname() return firstname
  
• private
• string firstname
• string lastname

15
Creating a Header File

• Too much code in one place
• Separation of unrelated code
• include rears its ugly head once again

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Header file example

• main.cpp
• include name.h
• include ltiostreamgt
• using namespace std
• int main()
• name myname
• myname.setfirstname("Matthew")
• myname.setlastname("Curry")
• cout ltlt "My first name is " ltlt
  myname.getfirstname() ltlt endl
• cout ltlt "My last name is " ltlt myname.getlastnam
  e() ltlt endl
• return 0

name.hinclude ltiostreamgtusing namespace
std class name public void
setfirstname(string firstname)
this-gtfirstname firstname
string getfirstname() return
firstname private string
firstname string lastname
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Further Separation

• name.h
• include ltstringgt
• using namespace std
• class name
• publicvoid setfirstname(string
  firstname)string getfirstname()
• privatestring firstnamestring lastname

name.cpp include name.h namesetfirstname(str
ing firstname) this-gtfirstname
firstname namegetfirstname() return
firstname
18
Control Structures

• Much like Java, thankfully
• If, if-else
• for, while, do-while,
• conditional operator
• switch

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If, If-Else

• If (condition)
• //do stuff
• else
• //do something else
• Remember An else matches the closest unmatched
  if!

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Conditional Operator

• ? is just a quick way to say if-else within an
  expression
• include ltiostreamgt
• using namespace std
• // The ugliest code youve ever seen
• int main()
• int x
• string count
• cin gtgt count
• count (x 0) ? "0" "many"
• cout ltlt "x " ltlt count ltlt endl

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For

• Syntax for (initialize test loop operation)
• for( ) creates an infinite loop
• for( conditional ) mimics while
• Scope works the same as in java Declare a
  counter within the for loop to be used within
• for (int x 0 x lt 1000 x) cout ltlt
  This is annoying!\n
• The break command exits the loop prematurely,
  while the continue command skips to the end of
  the loop

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While, Do-While

• int x 0
• while ( x lt 1000 )
• cout ltlt This is annoying, too!\n
• x 0
• do
• cout ltlt Shall I continue?\n
• while (x lt 1000)
• //Breaks and continues work here, too

23
Switch

• Switch is a replacement for huge if-else chains.
• switch(x)
• case 0
• case 1
• cout ltlt "Too few!\n"
• break
• case 2
• cout ltlt "Just right!\n"
• break
• default
• cout ltlt "Too many!\n"