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Fig. 1

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Fig 3

Fig. 4

    int x=11, y=22;
    float a=3.0, b=4.0, z;
    z= (float)(x/y) + a*b;
    NSLog(@" x=%i, z= %f \n",x,z);   

Fig. 5

Fig. 6

 x=11, z= 12.000000

    NSMutableArray  *yesNo = [NSMutableArray arrayWithObjects: @"yes", @"no", nil ];
    NSLog( @"array elements = %@,%@\nor:\n%@ ",[yesNo objectAtIndex:0], [yesNo objectAtIndex:1], yesNo);

Fig. 7

#import <Foundation/Foundation.h>
@interface tpwEmployee : NSObject {
@private
    char     * empName;
    float    empSalary;
    float    empHours;
}
-(void) setsalary: (float)sal andHours: (float)hrs;
-(float) getsalary;
@end

#import "tpwEmployee.h"

@implementation tpwEmployee

- (id)init
{
    self = [super init];
    if (self) {
        // Initialization code here.
        empName="noname";
        empSalary=1.0;
    }
    return self;
}

- (void)dealloc
{
    [super dealloc];
}

-(void) setsalary: (float)sal andHours: (float)hrs{
    empSalary=sal;
    empHours=hrs;
}

-(float) getsalary{
    return empSalary;
}

@end

    tpwEmployee * emp1;
    emp1 = [tpwEmployee alloc];
    emp1 = [emp1 init];
    NSLog(@"Employee salary=%f \n",[emp1 getsalary]);
    [emp1 setsalary: 123.25 andHours: 40.0];
    NSLog(@"Employee salary=%f \n",[emp1 getsalary]);
    [emp1 release];

    for(int nn=0; nn<4; nn++)
    {
        NSLog(@"nn=%i, nn*nn=%i \n",nn, nn*nn );
    }

    int mm=0;
    while(mm<4)
    {
        NSLog(@"mm=%i, mm*mm=%i \n",mm, mm*mm );
        mm=mm+1;
    }

    int kk=1;
    switch (kk)
    {
        case 0:
            NSLog(@"case kk=0 \n" );
            break;
        case 1:
            NSLog(@"case kk=1 \n" );
            break;
        case 2:
            NSLog(@"case kk=2 \n" );
            break;
    }

    int aa=1;
    if ( aa == 1 )
        NSLog(@"aa=1 \n");
   
    int bb=2;
    if ( bb == 1 )
        NSLog(@"bb = 1 \n");
    else
        NSLog(@"bb != 1 \n");

    int count=0;
    for(int cc=0; cc<4; cc++)
    for(int dd=0; dd<4; dd++)
    {
        count=count+1;
        if(cc == dd)
            NSLog(@"at count=%i, cc=%i == dd=%i \n",count,cc,dd);
    }

1. In the header of your class, after your @interface { } section, add an  @property directive for each variable that you want to create automatic getters and setters.  For our previous example:

• The possible setter attributes in the @property directive are (think about the memory management behavior you want):
• assign - setter uses simple assignment, typically used for scalar types of variable
• retain - setter invokes retain on the object upon assignment, and invokes release on the old object
  
• copy  -  setter uses a copy of the object for assignment, and the previous value is sent a release message.
• readonly - no setter is created
• nonatomic - disables the default atomic locking behavior,  atomic locks objects so other threads cant change the object
• (nonatomic, retain) - is perhaps the most common iOS attribute pair, since iOS is not-so-much multi-threaded
  

2. In the implementation file, of your class, add a corresponding @synthesize statement right after the @implementation.  For our previous example:

• Warning: if one of your synthesized variables was an object, you must remember to add [myobject release] to your dealloc method to prevent memory leaks.  For our previous example we did not have to do this, since empSalary and empHours were "floats" and not objects.
  

3. To use the automatically synthesized accessor methods:

•  To set an instance variable named myVar in an object named myObject to a value of 3, use:  [myObject setMyVar: 3]
  
• To get an instance variable  named myVar in an object named myObject, use:  [myObject myVar]
• Thus, our previous code example would become:
  

    tpwEmployee * emp1;
    emp1 = [tpwEmployee alloc];
    emp1 = [emp1 init];
    NSLog(@"Employee salary=%f   hours =%f \n",emp1.empSalary2,emp1.empHours2);
    emp1.empSalary2 = 123.25;
    emp1.empHours2 = 40.0;
    NSLog(@"Employee salary=%f   hours =%f \n",emp1.empSalary2,emp1.empHours2);
    [emp1 release];

Fig. 8