Engineering Problem Solving with C Fundamental Concepts

1
Engineering Problem Solving with C Fundamental
Concepts

• Chapter 7
• Structures

2
Structure Basics

• A structure is a collection of data values,
  called data members, that form a single unit.
• Unlike arrays, the data members can be of
  different types.

3
Structure Definition

• struct name
• variable declaration
• variable declaration
• .
• .
• the keyword struct announces that this is a
  structure definition

4
Example

• struct node
• int data
• node link
• the above defines a structure type
• the name of the structure type (node) is called
  the structure tag
• the identifiers declared inside the braces are
  called member names. Members can be declared to
  be of any valid C data type
• the tag node may now be used just like
  predefined types int, char, etc

5
Declaring Structure Variables

• struct node n1
• struct node head
• The structure n1 is a collection of smaller
  variables called member variables. The member
  variables are accessed using the dot (.)
  operator
• head n1
• n1.data 2
• n1.link NULL

2
6
Initializing Structures

• struct Rect
• double x
• double y
• double width
• double height
• struct Rect r1 0,0,5,10

7
Practice!
Write the C statements necessary to output the
value of the structure r1 defined in the previous
slide.
8
Assignment operator

• Assignment operator is defined for structure of
  the same type. (Compiler looks at tag, not
  composition.)
• struct Car
• char model, color
• double price
• int year
• struct Car Car1, Car2
• Car1.year 99
• Car1.price 18599.99
• Car1.color red
• Car1.model Contour
• / Copy all data from Car1 to Car2. /
• Car2 Car1

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Scope of a Structure

• Member variables are local to the structure.
• Member names are not known outside the structure.

10
Arrays of Structures

• Arrays of structures may be declared in the same
  way as other C data types.
• struct Car Ford20
• Ford0 references first structure of Ford array.
• Ford0.model Taurus

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Structures as Arguments to Functions

• When a structure is passed as an argument to a
  function, it is a call-by-value reference.
• Changes made to the formal parameters to not
  change the argument.
• A pointer to a structure may also be passed as an
  argument to a function.
• Changes made to the formal parameters also change
  the argument.

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Call by Value Example
Example struct simple int ival double
dval int main(void) void fun1(struct
simple s) struct simple s1 10,
1.5 fun1(s1) printf(i lf, s1.ival ,
s1.dval ) return 0 void fun1(struct simple
s) output?___________ s.ival s.dval

13
Pointers to Structures

• When using pointers to access structure members,
  the
• arrow operator is used.
• Example
• struct node
• int data
• struct node link
• struct node nptr, n
• nptr n
• nptr-gtdata 2
• nptr-gtlink NULL

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Pointers to Structures

• struct node
• int data
• struct node link
• int main(void)
• struct node nptr, n2, NULL
• void fun1(struct node)
• nptr n
• fun1(nptr)
• printf(i, n.data )
• return 0
• Output?___________________
• void fun1(struct node n)

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Structures as Return Values

• struct Rect
• double x,y,width, height
• int main(void)
• struct Rect mirror(struct Rect r)
• struct Rect r1 0,0,5,10, r2
• r2mirror(r1)
• .
• .

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Nested Structures

• Structure definitions may contain data members
  that are other structures
• Example
• struct Card
• char suit
• int rank
• struct Deck
• struct Card cards52
• int next_card 0