INFSCI 0015 Data Structures Lecture 1: Data Types

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INFSCI 0015 - Data StructuresLecture 1 Data
Types

• Peter Brusilovsky
• http//www2.sis.pitt.edu/peterb/0015-011/index.ht
  ml

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Compilation and errors

• The edit-compile loop
• 1. Edit program
• 2. Compile program
• 3. If there are errors, go back to 1
• you have got syntax error
• 4. Run it
• 5. If it produce wrong results go back to 1
• you have got semantic error

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Programming tools

• Editor
• PC Crimson Editor, PFE
• Mac BBEdit
• Unix emacs, vi, nedit
• Compiler
• PC LCC
• Unix cc/gcc
• IDE
• LCC-Win, MS Visual C, Borland, Leonardo

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Hello World - Compile Error

• include ltstdio.hgt
• main()
• printf(Hello World!\n)
• The semicolon is missing
• What happens when we compile this?

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Hello World - Compile Error

• What happens when we compile this?
• (5) unixs4 cc hello-nosemi.c
• "hello-nosemi.c", line 6 syntax error before or
  at
• (6) unixs4

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Hello World - Experiment 2

• include ltstdio.hgt
• main()
• printf(Hello World) /missing
  newline/
• What happens when we run this?

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Hello World - Experiment 2

• What happens when we run this?
• (13) unixs4 cc hello-nonewline.c
• (14) unixs4 ./a.out
• Hello World(15) unixs4

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Hello World - Experiment 3

• include ltstdio.hgt
• main()
• printf(Hello\n World\n) /extra
  newline/
• What happens when we run this?

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Hello World - Experiment 3

• What happens when we run this?
• (17) unixs4 cc hello-extranewline.c
• (18) unixs4 ./a.out
• Hello
• World
• (19) unixs4

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From Data to Data Structures
machine level data storage
0100110001101001010001
primitive data types
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3.1415
'A'
array
structure
data aggregates
high-level data structures
stack
queue
tree
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On each level...

• We do not want to be concerned with the way to
  represent objects of this level via objects of
  lower level
• We want to be concerned with the semantics of
  data on this level.
• What is it?
• What we can do with it?

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Primitive Data Types
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Primitive Data Types

• Integer data
• 1, 10, 999, 1000
• Floating point data
• 3.1415, 0.001, 2.0
• Characters
• 'A', 'B', '_', '_at_'

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999
3.1415
0.001
'_at_'
'A'
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Primitive data can be printed

• include ltstdio.hgt
• main()
• printf(Hello, World!\n)
• printf(Here are integers d d\n, 10, 99)
• printf(Here are floats f f\n, 3.1415,
  0.001)
• printf(Here are characters c c\n, 'A',
  '_at_')

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How printf works

• Simple form - prints a string
• printf("Some String\n")
• Note special symbols \t and \n
• Regular form
• printf("..d..f..c..\n",
• Expr1, Expr2, Expr3)
• specifications should match expressions

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Expressions?

• What is an expression?
• Anything that can have a value
• In C almost anything is an expression
• Expressions can have values of different type
• A literal constant is an expression
• 4 3.1415 99 'A' 0.0001

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More control over printing

• include ltstdio.hgt
• main()
• printf("Hello, World!\n")
• printf("Integer 5d\n", 10)
• printf("Float 4.2f\n", 3.1415)
• printf("Characters c\n", 'A')
• printf("Mix 08d 8.5f c\n", 99, 0.001, '_at_')

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Summary of print control

• d prints a decimal integer
• 6d prints a decimal integer at least 6 char wide
• f prints a floating point
• 6f prints a floating point at least 6 char wide
• .2f prints a floating point, 2 characters after
  decimal point
• 6.2f prints a floating point at least 6 char
  wide and 2 characters after decimal point

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We can calculate

• include ltstdio.hgt
• main()
• printf("Let's calculate!\n")
• printf("1234 4321 5d\n", 1234 4321)
• printf("23.141510 7.1f\n", 23.141510)
• printf("5/2 d\n", 5/2) / int division /
• printf("5.0/2 f\n", 5.0/2)
• / type conversion /
• printf("52 d\n", 52) / mod operation /

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Type conversion

• Automatic type conversion
• If operands are of the same type, the result will
  be of this type too
• If operands are of different types, they will be
  converted to the broader type (I.e., int to
  float) before the calculation
• Later we will learn about assignment conversion
  and direct conversion

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Before next lecture

• Complete your CourseWeb assignment (6pt)
• Try Course static Web site
• Check Syllabus
• Install / try program development tools
• Get and check one of the C books
• Download, compile and run examples