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How to implement a stack in Objective-C

, 23 Jul 2011 CPOL
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Stack implementation for Objective-C.

Stack is a very commonly used data structure. But Objective-C does not have this data structure. So I use NSMutableArray to implement the basic functions push and pop.


@interface HsuStack : NSObject {
    NSMutableArray* m_array;
    int count;
- (void)push:(id)anObject;
- (id)pop;
- (void)clear;
@property (nonatomic, readonly) int count;


#import "HsuStack.h"
@implementation HsuStack
@synthesize count;
- (id)init
    if( self=[super init] )
        m_array = [[NSMutableArray alloc] init];
        count = 0;
    return self;
- (void)dealloc {
    [m_array release];
    [self dealloc];
    [super dealloc];
- (void)push:(id)anObject
    [m_array addObject:anObject];
    count = m_array.count;
- (id)pop
    id obj = nil;
    if(m_array.count > 0)
        obj = [[[m_array lastObject]retain]autorelease];
        [m_array removeLastObject];
        count = m_array.count;
    return obj;
- (void)clear
    [m_array removeAllObjects];
    count = 0;

Objective-C has a type called id, that acts in some ways like a void*, though it's meant strictly for objects. Objective-C differs from Java and C++ in that when you call a method on an object, it doesn't need to know the type. That method simply just has to exist. This is refered to as message pasing in Objective-C.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Cloud Hsu
Architect LPI
Taiwan Taiwan
CloudBox cross-platform framework. (iOS+ Android)
Github: cloudhsu
1. Super Baby Pig (iOS+Android)
2. God Lotto (iOS+Android)
2. Ninja Darts (iOS)
3. Fight Bingo (iOS)

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Comments and Discussions

GeneralReason for my vote of 5 kl;\ Pin
Ameen Abudbush30-Jul-11 19:32
memberAmeen Abudbush30-Jul-11 19:32 
BugObject-C? Pin
AspDotNetDev18-Jul-11 12:46
mvpAspDotNetDev18-Jul-11 12:46 
BugA bug? Pin
xesique17-Jul-11 22:15
memberxesique17-Jul-11 22:15 

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