Please tell me how to convert bytes to NSInteger/int in objective-c in iPhone programming?
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What do you mean exactly by convert bytes to int?Jason Coco– Jason Coco2010-04-27 04:43:38 +00:00Commented Apr 27, 2010 at 4:43
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'bytes'? What kind of bytes? Data? string? something over the net? xml? huh?bbum– bbum2010-04-27 04:47:40 +00:00Commented Apr 27, 2010 at 4:47
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1@bbum, the "value" does not come with an "s" in the question title.ohho– ohho2010-04-27 04:52:31 +00:00Commented Apr 27, 2010 at 4:52
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5 Answers
What do you mean by "Bytes"? If you want convert single byte representing integer value to int (or NSInteger) type, just use "=":
Byte b = 123;
NSInteger x;
x = b;
as Byte (the same as unsigned char - 1 byte unsigned integer) and NSInteger (the same as int - 4 bytes signed integer) are both of simple integer types and can be converted automatically. Your should read more about "c data types" and "conversion rules". for example http://www.exforsys.com/tutorials/c-language/c-programming-language-data-types.html
If you want to convert several bytes storing some value to int, then convertion depends on structure of these data: how many bytes per value, signed or unsigned.
2 Comments
ohho
this is an objective-c question. NSInteger is defined in NSObjCRuntime.h and the first #import in NSObjCRuntime.h is <objc/objc.h>, so I consider the objective-c tag is ok. (Just my guess), the rationale behind this question is: someone new to objective-c may not see the difference between a NSInteger and a NSNumber at first sight.
NSResponder
NSInteger is a typedef, not an objective-C keyword. It's still a plain C question.
If by byte, you mean an unsigned 8 bit value, the following will do.
uint8_t foo = 3; // or unsigned char foo...
NSInteger bar = (NSInteger) foo;
or even
NSInteger bar = foo;
1 Comment
John Ballinger
Awesome that work for me. Thanks heaps, I have been searching ages for how to do this with hex. e.g. Sing8 foo = 0xF4 converting that to an int
My guess:
unsigned char data[] = { 0x00, 0x02, 0x45, 0x28 };
NSInteger intData = *((NSInteger *)data);
NSLog(@"data:%d", intData); // data:675611136
NSLog(@"data:%08x", intData); // data:28450200
So, beware of byte-order.
Comments
NSInteger x = 3;
unsigned char y = x;
int z = x + y;
Use the "=" operator.
1 Comment
suse
Can u show me with a small example? i want to knw is there any inbuilt method to convert bytes to int.