macOS Does @"abcef" mean a temp string object is created?

[zippyfly]

In code

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    NSString *myStr = @"ABCDEFG";
	
	NSLog(@"Length: %i", [myStr length]);
	
	NSLog(@"Pointer: %p\n\n", myStr);

	myStr = @"Hi";
	
	NSLog(@"Length: %i", [myStr length]);

	NSLog(@"Pointer: %p", myStr);

	[pool drain];
    return 0;
}

Does myStr get assigned a POINTER to temporarily created string object, which gets created when we use the @ in front of the delimited text?

i.e., because myStr would hold a pointer to a string object, I am wondering what the @ operator does to create that object? I would like to understand what is going on in the background with this assignment, since in other cases:

	int x = 50;
	int *xPtr;
	
	xPtr = &x;
	
	NSLog(@"*xPrt: %i", *xPtr);

But in the string case, it's not *myStr = @"String"

?

 

[lee1210]

See:
http://developer.apple.com/documentation/Cocoa/Conceptual/Strings/Articles/CreatingStrings.html

It describes the @"" NSString literal syntax, lifetime of the object created, etc. You do get a pointer to an NSString object that will respond to all of the same messages any other NSString object would. You don't need to/shouldn't send retain or release messages to these objects, though.

-Lee

 

[zippyfly]

Thanks.

 

[admanimal]

Just to clarify, the @ symbol in Objective-C isn't an operator like * or &. It's just a special character that Objective-C likes to use to help it parse special keywords or NSString literals. For example, the @ in @property doesn't really operate on something called property- it just helps form a special keyword.

 

[zippyfly]

Thanks for reminder; I understand that (Obj-C being a superset semi-preprocessor on top of ANSI C) for keywords but also overlooked that it applies to the string literals, until you reminded me.