CPS 125: Digital Computation and Programming

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CPS 125 Digital Computation and Programming

• Structure Types

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Outline

• User-Defined Structure Types
• Structure Type Data as Input and Output
  Parameters
• Functions whose Result Values are Structured
• Case Study
• Common Programming Errors

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Structure Data Type

• Simple data type
• int, long, float, double, char,
• Structure type
• A composite data type, which consist of several
  data items with simple or composite data types
• e.g. Description of a planet
• Name, Diameter, Moons, Orbit time, Rotation time
• Actual values
• Jupiter, 142980(km), 16, 11.9(yr), 9.925(hr)

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Definitions

• struct date
• int month, day, year
• hire_date, current_date
• typedef struct
• int month, day, year
• date_t
• date_t hire_date, current_date

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Definition for Planet

• define STRSIZE 10
• typedef struct
• char nameSTRSIZE
• double diameter
• int moons
• double orbit_time,
• rotation_time
• planet_t
• planet_t blank_planet , 0, 0, 0, 0
• planet_t previous_planet, current_planet
• previous_planet current_planet

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Hierarchical Structure Type

• typedef struct
• double diameter
• planet_t planets9
• char galaxySTRSIZE
• solar_sys_t

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Referencing Components

• planet_t current_planet, plnp
• Two operators
• Component selection operator (a period .)
• e.g. current_planet.diameter 142980
• strcpy(current_planet.name, Jupiter)
• Indirect component selection operator (an arrow
  -gt)
• e.g. plnp (planet_t )malloc(sizeof(planet_t))
• plnp-gtdiameter 142980
• strcpy(plnp-gtname, Jupiter)
• plnp-gtname ltgt (plnp).name (plnp.name?)

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Operator Precedence

• aj, f(), a.name, p-gtname left
• , -- (postfix) left
• , --, (prefix) !, -, , (unary) , right
• (type name) right
• , /, left
• , - left
• lt, gt, lt, gt left
• , ! left
• left
• left
• , , -, , /, right

high
low
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• typedef struct
• char city21
• char state3
• char zip7
• address_t
• typedef struct
• int id_num
• char name15
• address_t addr
• double income
• family_rec_t next
• family_rec_t
• family_rec_t family1, family2, fap

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• family1.id_num 5
• strcpy(family1.name,Jones)
• strcpy(family1.addr.city,Toronto)
• strcpy(family1.addr.state,ON)
• strcpy(family1.addr.zip,M5G1X1)
• family1.income 6000.00
• family1.next family2
• / initialization on family2 /
• fptr family1

A linked list
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• Define a type named long_lat_t that would store
  longitude or latitude values. Include components
  named degrees, minutes and direction (N, S,
  E, or W)
• A catalog listing for a textbook consists of the
  authors names, the title, the publisher, and the
  year of publication. Declare a structure type
  catalog_entry_t and a variable book, and write
  statements that store the relevant data for this
  textbook in book.

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Structure Type used in Functions

• / Displays with labels all components of a
  planet_t structure /
• void print_planet(planet_t pl) / input - one
  planet structure /
• printf("s\n", pl.name)
• printf(" Equatorial diameter .0f km\n",
  pl.diameter)
• printf(" Number of moons d\n",
  pl.moons)
• printf(" Time to complete one orbit of the
  sun .2f years\n",
• pl.orbit_time)
• printf(" Time to complete one rotation on
  axis .4f hours\n",
• pl.rotation_time)
• Call the function print_planet(current_planet)

Input parameter
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• / Determines whether or not the components of
  planet_1 and planet_2 match /
• int
• planet_equal(planet_t planet_1, / input -
  planets to /
• planet_t planet_2) /
  compare /
• return (strcmp(planet_1.name,
  planet_2.name) 0
• planet_1.diameter
  planet_2.diameter
• planet_1.moons planet_2.moons
  
• planet_1.orbit_time
  planet_2.orbit_time
• planet_1.rotation_time
  planet_2.rotation_time)
• Call the function if (planet_equal(current_planet
  , previous_planet) 1)

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• int scan_planet(planet_t plnp) / output -
  address of planet_t /
• int result
• result scanf("slfdlflf",
  (plnp).name,
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  (plnp).diameter,
• 
  (plnp).moons,
• 
  (plnp).orbit_time,
• 
  (plnp).rotation_time)
• if (result 5)
• result 1
• else if (result ! EOF)
• result 0
• return (result)
• Call the function if (scan_planet(current_planet
  ) 1)

Output parameter
plnp-gtname, (plnp-gtdiameter), (plnp-gtmoons), (p
lnp-gtorbit_time), (plnp-gtrotation_time)
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• / Gets and returns a planet_t structure /
• planet_t get_planet(void)
• planet_t planet
• scanf("slfdlflf", planet.name,
• planet.diameter,
• planet.moons,
• planet.orbit_time,
• planet.rotation_tim
  e)
• return (planet)
• Call the function current_planet get_planet()
• With the same effect as scan_planet(current_plan
  et)

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Abstract Data Type

• A user-defined data type combined with a set of
  basic operations.
• e.g. data type planet_t
• operations scan_planet, print_planet,
  planet_equal
• e.g. data type complex_t (complex number abi)
• operations scan, print, add, subtract,
  multiply, divide, abs

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Array of Structures

• Structure data as a record, array as a database
• typedef struct
• int id
• double gpa
• student_t
• typedef struct
• double x, y
• point_t
• student_t stu_listMAX_STU
• point_t polygonNUM_PTS

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Array of Structures

• for (i 0 i lt MAX_STU i)
• scan_student(stu_listi)
• for (i 0 i lt MAX_STU i)
• printf(d\t.2f\n, stu_listi.id,
  stu_listi.gpa)

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Case Study

• Problem Write a program that takes a measurement
  in one unit (e.g. 4.5 quarts) and converts it to
  another unit (e.g. liters).
• Structured data type
• unit_t components
• name / e.g. milligrams /
• abbrev / e.g. mg /
• class / liquid_volume, distance, or
  mass /
• standard / number of standard units equivalent
  to this /

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Common Programming Errors

• Always use the right operation on selected
  component
• e.g. If selected component is string, cannot use
  assignment operator
• If selected component is array, when passing to
  a function as output, no required
• No comparison operator on structure types
• Cannot directly used in printf and scanf