CS 126 Lecture P5: Abstract Data Type Outline Introduction Stacks - - PowerPoint PPT Presentation

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CS 126 Lecture P5: Abstract Data Type Outline Introduction Stacks - - PowerPoint PPT Presentation

Feb 15, 2023 389 likes •626 views

CS 126 Lecture P5: Abstract Data Type Outline Introduction Stacks (and queues) Stack and queue applications CS126 6-1 Randy Wang Data Type and ADT CS126 6-2 Randy Wang Interface, Implementation, and Client Im plem entation

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CS 126 Lecture P5: Abstract Data Type

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CS126 6-1 Randy Wang

Outline

  • Introduction
  • Stacks (and queues)
  • Stack and queue applications
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CS126 6-2 Randy Wang

Data Type and ADT

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CS126 6-3 Randy Wang

Interface, Implementation, and Client

Volum e C hannel

C lient Interface Im plem entation

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CS126 6-4 Randy Wang

Advantages of ADT

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CS126 6-5 Randy Wang

“Non-ADTs”

interface: typedef struct {int p; int q;} Rational; client: Rational a; a.p = 3;

Non-ADT

interface: typedef struct {int p; int q;} Rational; client: Rational a; setRational(&r, 3);

void setRationalP(Rational *r; int x); ADT

implementation: void setRationalP(Rational *r; int x)

{r->p = x;}

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CS126 6-6 Randy Wang

Outline

  • Introduction
  • Stacks (and queues)
  • Stack and queue applications
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CS126 6-7 Randy Wang

Stack and Queue Definitions

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CS126 6-8 Randy Wang

Interface, Implementation, and Client

  • “Client” needs to know how to use the “interface”
  • “Implementation” needs to know what “interface” to

implement

Volum e C hannel

C lient (m yprog.c) Interface (stack.h) Im plem entation (stack.c)

#include #include

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Post-increment: s[N] = item; N+=1; Pre-decrement: N-=1; return s[N];

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Index of 1st empty slot Time

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Opposite of malloc: gives memory back to computer

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CS126 6-13 Randy Wang

Demo Linked List Stack

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for array

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CS126 6-15 Randy Wang

Outline

  • Introduction
  • Stacks (and queues)
  • Stack and queue applications
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infix: a + b postfix: a b + infix: 9*16^4 + 7*16^3+5*16^2 + 3*16^1

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number of inputs to main array of input strings number of characters in string for each character in the string pop two items, add them up, and push result back deal with digits: pop the previous digits, multiply the number by 10, add the new digit, and push the partial answer back.

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CS126 6-18 Randy Wang

Demo Postfix Calculator

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CS126 6-20 Randy Wang

“First Class” ADTs

  • So far, only one stack (or queue) per program
  • “First Class” ADTs
  • An ADT that is just like a built-in C type
  • Can declare multiple instances of them
  • Pass specific instances of them to the interface functions as

inputs

{ Stack s1, s2; s1 = stackInit(); s2 = stackInit(); ... stackPush(s1, 5); stackPush(s2, 8); } { ... stackInit(); ... stackPush(5); }

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B

Take one element from the T queue at a time, add it to the A queue, and repeat until the T queue is empty. (Not most efficient.)

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CS126 6-22 Randy Wang

Conclusion

  • ADT is one of the most important concepts for managing

software engineering complexity

  • Learn to identify the possible use of ADTs in a program
  • Learn the proper decomposition and encapsulation using

interface and implementation files