★ ★ some objective-c code Wrong?

The following code, compile time error, which is the red part of the code
MYHelloWorld.h: 7:1: error: stray '@' in program
MYHelloWorld.m: 5:1: error: stray '@' in program

 
# Import  

@ Interface MYHelloWorld: NSObject {
NSString * _userName; 
} 

 @ property (nonatomic, retain) NSString * userName;  

- (Id) initWithUserName: (NSString *) userName; 
- (Void) helloWorld; 

@ End 

 
# Import "MYHelloWorld.h" 

@ Implementation MYHelloWorld 

 @ synthesize userName = _userName;  

- (Id) initWithUserName: (NSString *) userName {
self = [super init]; 
_userName = [userName copy]; 
return self; 
} 

- (Void) helloWorld {
NSString * text = [NSString stringWithFormat: @ "% @, Hello World!", _userName]; 
printf ([text UTF8String]); 
} 

- (Void) dealloc {
[_userName Release]; 
[Super dealloc]; 
} 

@ End 

Reply:
e ... printf function of c iostd library to include it
Reply:
printf replaced NSLog
Reply:
No error.
Check spelling and punctuation in English is wrong.
Reply:
Try unified naming it. . ?
Reply:

 # import "MYHelloWorld.h" 

@ Implementation MYHelloWorld 

@ Synthesize userName; 

- (Id) initWithUserName: (NSString *) userName {
self = [super init]; 
_userName = [userName copy]; 
return self; 
} 

- (Void) helloWorld {
NSString * text = [NSString stringWithFormat: @ "% @, Hello World!", _userName]; 
printf ([text UTF8String]); 
} 

- (Void) dealloc {
[_userName Release]; 
[Super dealloc]; 
} 

@ End 

Reply:
_userName If not, do not release the alloc of it. . .
Reply:
@ Property (copy) NSString * userName;
Reply:
Look. . . . . .