Arash Rafiey

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Arash Rafiey

• arafieyh_at_cs.sfu.ca
• TA Xu Cheng
• xuc_at_cs.sfu.ca
• Office Hours
• M-W 1030 1130

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How Create a C Program
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• includeltiostreamgt
• using namespace std
• void main()
• coutltltHello World
• If your compiler gives error then

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• includeltiostream.hgt
• void main()
• coutltltHello World
• coutltltendl // for going to new line
• coutltlt good bye
• cout is an object for printing out some thing
• on the screen.

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• includeltiostream.hgt
• void main()
• coutltltHello World \n
• coutltlt good bye
• we can use \n instead of coutltltendl

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How to run your program

• Using Linux or unix
• g myFile.cpp
• ./a.out
• g myFile.cpp myFile.out
• ./myFile.out

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Declare Statement Variable

• Each variable must be declare before use
• Each variable has a type
• For example
• int , char, float.
• int for Integer type
• char for character like A
• float for real number

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Example

• int LuckyNumber17
• float RealNumber
• char aA

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Identifiers

• Identifier name of a variable, function, or
  class
• Rules for identifiers in C
• 1 Can be made up of letters, digits, and the
  underscore (_) character
• 2 Cannot start with a digit
• 3 Cannot use other symbols such as ? or
• 4 Spaces are not permitted inside
  identifiers
• 5 You cannot use reserved words
• 6 They are case sensitive

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Self Check

• 1. What is the type of the values 0 and 0?
• 2. Which of the following are legal identifiers?
• Greeting1gvoid101dalmatiansHello,
  Worldltgreetinggt

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Answer

• int and char
• Only the first two are legal identifiers

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Syntax Variable Definition

• typeName variableName valueor typeName
  variableName
• Example
• int numbe 12
• Purpose
• To define a new variable of a particular type and
  optionally supply an initial value

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The Assignment Operator

• Assignment operator
• Not used as a statement about equality
• Used to change the value of a variable
• int number1
• int number2, number3 number1number2number3
  88

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• number2number2-1
• number3number21

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How to read a variable

• includeltiostreamgt
• using namespace std
• void main()
• int number
• coutltltplease enter a number \n
• cingtgtnumber
• numbernumber1
• coutltltthe number is ltltnumber

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Integer Types

• The short, int and long Integer Types
• A short integer is at least 16 bits
• A int integer is at least as big as short
• A long integer is at least 32 bits and at
• least as big as int .

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• E.g. A 16-bit int might run from -32768 to 32767
• The sizeof operator returns the size (in bytes)

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• includeltiostream.hgt
• int main()
• int n_int INT_MAX
• short n_short SHRT_MAX
• long n_long LONG_MAX
• cout ltlt int is ltlt sizeof (int) ltlt bytes
  ltlt endl
• cout ltlt short ltlt n_short ltlt endl
• cout ltlt long ltlt n_long ltlt endl
• return 0

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• int is 4 bytes
• Maximum values
• Short 32767
• Long 2147483647

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Characters and small integers

• includeltiostream.hgt
• int main()
• char ch M // assign ASCII code
• int a ch
• cout ltlt ASCII code ltlt ch ltlt is ltlt a
  ltlt endl
• ch ch 1
• a ch
• cout ltlt ASCII code ltlt ch ltlt is ltlt a ltlt
  endl
• return 0

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Output

• M is 77
• N is 78

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Boolean type

• bool isReady true
• int ans true // ans assigned 1
• int promise false // promise assigned 0
• bool start -100 // true
• bool stop 0 // false

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Floating-point number

• E.g.
• 12.34
• 9300.3
• 0.02
• 8.0
• We have
• float, double, long double

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Arithmetic operators

• Summation
• Multiplication
• Division /
• Subtraction -

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Operator Precedence

• int number 3 4 5 // 35 or 23?
• float logs 120 / 4 5 // 150 or 6??

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Type Casting

• Conversion between types
• (typeName) value // c
• typeName (value) // c
• e.g.
• cout ltlt int(A) ltlt endl // 65
• float one,
• int two
• one 1.9 2.1
• two (int) 1.9 (int) 2.1

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Functions

• Building blocks of programs
• A function
• Has an input and an output
• Contains a set of instructions
• x sqrt(16) // returns 4

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Syntax

• typeName functionName (typeName varName_1, )
• BODY
• .
• .
• .
• return value

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Examples of functions

• int sum (int firstValue, int secondValue)
• int final
• final firstValue secondValue
• return final
• void main()
• int a 1
• int b 2
• int total sum(a,b)
• cout ltlt Total is ltlt total ltlt endl

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Arrays

• An array is a data form that holds several values
  of the same type
• Syntax
• typeName arrayNamevalue
• e.g
• int someArray3
• Index starts from 0!!!
• someArray0 1
• someArray2 2

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Initializations Rules for Arrays

• int array4 2,6,4,5
• int secondArray4
• secondArray4 5,6,7,8 // error!!!
• secondArray array //error!!!
• float Hotel5 1.1, 2.2
• long total500 0

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• short array 1,2,3,4

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String

• Series of characters stored in a consecutive
  bytes
• Create a string as an array but the last element
  must be the null character \0
• e.g
• char dog5 b,e,a,u,x //NOT!!
• char dog6 b,e,a,u,x,\0 //
  STRING!!

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More examples

• char dog5 beaux //a better way
• null character is implicitly included.
• char namec // compiler counts
• char boss8Arvind

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• includeltiostream.hgt
• int main()
• int arSize 20
• char namearSize
• char dessertarSize
• cout ltlt Enter your name ltlt endl
• cin gtgt name
• cout ltlt Enter your dessert ltlt endl
• cin gtgt dessert
• cout ltlt name ltlt has selected ltlt dessert ltlt
  endl
• return 0

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Another way to read a string

• includeltiostream.hgt
• int main()
• int arSize 20
• char namearSize
• char dessertarSize
• cout ltlt Enter your name ltlt endl
• cin.getline(name, arSize) // reads through
  newline
• cout ltlt Enter your dessert ltlt endl
• cin.getline(dessert, arSize)
• cout ltlt name ltlt has selected ltlt dessert ltlt
  endl
• return 0

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The String class

• To define strings more easily
• Include the string class
• includeltstringgt
• string str_1 jaguar

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Assignment Concatenation Appending

• char char_120
• char char_220 jaguar
• string str_1
• string str_2 panther
• char_1 char_2 // INVALID!!
• str_1 str_2 // VALID!!

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Appending

• string str_3
• str_3 str_1 str_2 // join str_1 and str_2
• str_1 str_2 // add str_2 to the end of str_1

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More string operations

• Copying include ltcstringgt
• strcpy(char_1, char_2) //copy char_2 into
  char_1 strcat(char_1, char_2) //append char_2 to
  char_1
• Size of a string
• char charOne20 p,i,e
• string strOne pie
• strlen(charOne)
• strOne.size()

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Increment Decrement

• Increment
• int a 20
• int b 20
• cout ltlt a ltlt a ltlt b ltlt b ltlt endl
• cout ltlt a ltlt a ltlt b ltlt b ltlt
  endl
• cout ltlt a ltlt a ltlt b ltlt b ltlt endl

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• a 20 b20
• a 20 b21
• a21 b21
• int x 5
• int y x

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Decrement --

• Same rules as increment ( i.e. )

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Loops

• different types
• for
• while
• etc.

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For Loop

• for(initialValue test-expression
  update-expression)
• BODY

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Example

• includeltiostream.hgt
• int main()
• int a
• for (a 0 a lt 10 a )
• cout ltlt a ltlt endl
• return 0

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While loop

• while(test-expression)
• BODY

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Example

• includeltiostream.hgt
• int main()
• int arSize 20
• char namearSize
• cin gtgt name
• int a 0
• while (namea ! \0)
• cout ltlt namea ltlt endl
• a
• return 0

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Conditional Statements

• if statements
• Syntax
• if (condition)
• IF_BODY
• else
• ELSE_BODY

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Conditions

• Relational Expressions
• Comparisons
• e.g
• tests equality
• gt is greater?

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Example

• int number
• cin gtgt number
• if ( number lt 0)
• cout ltlt Negative Value ltlt endl
• else
• cout ltlt Non-negative Value ltlt endl

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Comparing two strings

• includeltiostream.hgt
• int main()
• int arSize 20
• char name1arSize
• char name2arSize
• coutltltString1ltltendl
• cingtgtname1
• coutltltString2ltltendl
• cingtgtname2

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• int len1,len2,a
• len1strlen(name1)
• len2strlen(name2)
• bool flagtrue
• if (len1 ! len2 )
• coutltltdifferent
• else
• for (a0 name1aname2a)
• if (alen1)
• coutltltThe same
• else
• coutltltdifferent

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Sort an Array of Integer

• includeltiostream.hgt
• int main()
• int arSize 20
• int ArrayNumberarSize
• int indx
• for(index0 index lt20 index)
• coutltltenter an integerltltendl
• cingtgtArrayNumberindex

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• int i,j
• int temp
• for( i1 ilt 20i)
• for (j0 jlt ij)
• if (ArrayNumber j gt ArrayNumber j1)
• temp ArrayNumber j
• ArrayNumber j ArrayNumber j1
• ArrayNumber j1temp