Using static variables->Objective C

Question

I am getting warnings when declaring and using the static variables.

static int m_chSequenceChar; 

@interface data : NSObject
{

}
-(id)init;
-(void)initialze;
@end

@implementation data

- (id)init
{

 m_chSequenceChar= 0;
}

+ (void)initialize
{

  m_chSequenceChar= 0;

}

@end

Warning: 'm_chSequenceChar' defined but not used

EDITED:

data.h
------

static int m_nMessageId;      //Message ID
static int m_uSessionId;      //Session ID
static int m_chSequenceChar;  //Sequence ID

static int* m_pData;          //Integer buffer to carry data
static int m_uDataSize;       //Datasize

@interface data : NSObject {

    @public


}


data.m
------

@implementation data

+ (void)initialize
{
    m_uSessionId    = 0;
    m_chSequenceChar= 0;

    m_nMessageId    = 0;
    m_pData         = 0;              
    m_uDataSize     = 0; 

}
- (id) initWithID:(int) uMessageId withData:(id)pData withSize:(size_t) uDataSize
{
        if(self=[super init])
        {
           // Initialize the member variables
            m_uSessionId    = 0xFF;
            m_chSequenceChar= 10;

           // Initialize values from derived class
            m_nMessageId    = uMessageId;
            m_pData         = (int*)pData;              
            m_uDataSize     = (int)uDataSize;            
        }
        NSLog(@"Data size:%d",uDataSize);
        NSLog(@"m_pData:%d",m_pData);
        NSLog(@"pData:%d",pData);

     data* dat = [data alloc];
     return self;   
}

@end

user557219 · Accepted Answer · 2011-05-06 08:55:07Z

1

That’s because you’re not reading the value of m_chSequenceChar in your code. If you’re not reading it, you’re not using it, hence the warning.

Also, are you sure you want to reset m_chSequenceChar to 0 whenever an instance of data receives -init? In general, +initialize should be enough. And, in fact, you don’t even need to explicitly set it to 0.

answered May 6, 2011 at 8:55

user557219

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7 Comments

user557219 Over a year ago

@Beata Have you changed your code to use that variable? If so, edit your question and paste the code.

user557219 Over a year ago

@Beata Your new code does not read/use m_chSequenceChar either: you’re assigning it values but you are not reading/using the variable at all. And the fact that you’re assigning it a value inside -init makes me thing you do not want a class variable in the first place.

Angus Over a year ago

@Bavarious: I want it as the class variables.See in the edited code i'm not using -(init) method to intialise.I'm using +(void)initialize function.I'm using all the variables on another function inside the same class to print the values.When called that method

user557219 Over a year ago

@Beata You do have an instance initialiser: -initWithID… and you are assigning a value to that variable — see m_chSequenceChar= 10;. In fact, you’re using the instance initialiser to assign values to class variables, the same variables you also assign in +initialize. And your pasted code does not show this ‘another function’ that is supposed to read the variable, which is what I had asked you in my first comment.

user557219 Over a year ago

@Beata Also, by declaring those variables in the header file you end up declaring them in every implementation file that imports/includes that header file. Move the declaration of those variables to the (single) implementation file that actually uses them.

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