C workshop Yuli Kaplunovsky - [e-mail] Today - Introduction to C

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C workshopYuli Kaplunovsky -
yuli_at_magniel.comToday - Introduction to C
Recommended book The C programming Language /
Kernighan Ritchie
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My first program

• include ltstdio.hgt
• void main()
• printf("Hello World!\n")

Output Hello World!
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C structure

• Function oriented (goto is not recommended)
• First function is always called main
• Contains many libraries (e.g. stdio.h, stdlib.h,
  math.h) with many predefined functions.
• CaSe SeNsItIvE (e.g. Main instead of main
  wont work)
• ALWAYS USE
• Indentation
• Meaningful names for functions and variables
• Plenty of remarks

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Variables

• int an integer number maximum value is
  2,147,483,647 (or 231) minimum value is
  -2,147,483,648
• double real number, represented as floating
  point (64 bits long)
• char represents a single character

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Variables sample 1

• include ltstdio.hgt
• void main()
• int I,J,K
• I 10
• J 20
• K I J
• printf("K is d\n", K)

Output K is 30
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Variable sample 2

• include ltstdio.hgt
• void main()
• double X,Y,Z
• X 10.0
• Y 20.0
• Z X / Y
• printf("Z is g\n", Z)

Output Z is 0.5
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while

• include ltstdio.hgt
• / Print Fahrenheit-Celsius table
• for fahr 0, 20, .., 300 /
• void main()
• int fahr, celsius
• int lower, upper, step
• lower 0 / lower limit of temerature
  table /
• upper 300 / upper limit /
• step 20 / step size /
• fahr lower
• while ( fahr lt upper )
• celsius 5 (fahr - 32) / 9
• printf("d\td\n", fahr, celsius )
• fahr fahr step

Output 0 -17 20 -6 40 4 60
15 80 26 100 37 120 48 140
60 160 71 180 82 200 93 220
104 240 115 260 126 280 137 300
148
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for

• Syntax for ( initialization condition do )
  block
• include ltstdio.hgt
• void main()
• int I
• printf("I ")
• for ( I 0 I lt 10 I )
• printf("d, ", I )
• printf("\n")

Output I 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
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for - another example
Output 0 -17.7778 20 -6.66667 40
4.44444 60 15.5556 80 26.6667 100
37.7778 120 48.8889 140 60 160 71.1111 180
82.2222 200 93.3333 220 104.444 240
115.556 260 126.667 280 137.778 300 148.889

• include ltstdio.hgt
• void main()
• int fahr
• for ( fahr 0 fahr lt 300 fahr fahr
  20 )
• printf("d g\n", fahr, (5.0 / 9.0)
  (fahr - 32) )

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if

• if ( condition ) block 1 else
  block 2 (optional)
• Exampleif ( Y gt X ) Z Xelse Z Y
• For comparisons use gt lt lt gt
• Important remark a block should be surrounded
  with if it contains more than one command.

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If - multiple conditions

• if ( (condition1 condition2 ) condition3)
  ...
• Examplesif ( Y gt X Y gt Z ) Z Xint
  bTerminate if ( I 10 bTerminate )
  break
• break is used to get out of for while loops
• condition2 is FALSE when bTerminate is 0
  and is TRUE when bTerminate is NOT 0

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Functions

• Return-value function-name( parameters )
  return value
• Calling the functionI function-name( 10, 20 )

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Function example

• include ltstdio.hgt
• int Add2( int A, int B )
• int C
• C A B
• return C
• void main()
• int I
• I Add2( 10, 20 )
• printf("Add2 function returns d\n", I)

Output Add2 function returns 30
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Arrays

• ALWAYS start from 0Last item is N-1
• Exampleint Ar10Ar0 22Ar9 Ar0
  22I 4 ArI ArI1

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• include ltstdio.hgt
• // Guess what this program does...
• void main()
• double X10 2, 4.2, 11.2, 3, 99.2,
  -23.2, 33, 11, 43, 9
• double Y
• int I, J
• for ( I 0 I lt 9 I )
• for ( J I1 J lt 10 J )
• if ( XI gt XJ ) // Switch
  variables in array
• Y XI
• XI XJ
• XJ Y
• // print results
• for ( I 0 I lt 10 I )
• printf("g, ", XI)

Output -23.2, 2, 3, 4.2, 9, 11, 11.2, 33, 43,
99.2,