NSData problems and viewing buffer data in hex
NSData problems and viewing buffer data in hex
- Subject: NSData problems and viewing buffer data in hex
- From: William Squires <email@hidden>
- Date: Wed, 07 May 2014 11:21:05 -0500
Quickie question: Does [NSData getBytes:range:] return <range>.length bytes into the buffer specified, even if some of the bytes may be '\0' (terminating null), so long as range is valid? I'm trying to read in a specified record from a random-access file (record length is 1000 bytes = kRecSize), and I have a self.fileContents that's an @property (nonatomic, strong) NSData *fileContents, which I set up as follows:
"FSSBorr.m"
-----------
#import "FSSBorr.h"
char buffer[kRecSize + 1]; // <-file scope
#pragma mark "Private Suff"
@interface FSSBorr ()
@property (nonatomic, assign) BORR_REC theRec;
@property (nonatomic, copy) NSString *fileName; // These two are set up in my initWithFile:
@property (nonatomic, strong) NSData *fileContents; // ditto
@end
@implementation FSSBorr
...
-(void)loadRec:(NSUInteger)index
{
NSUInteger byteOffset = index * kRecSize;
NSRange recordRange = NSMakeRange(byteOffset, kRecSize);
char *c = &buffer[0];
char *p = (char *)(&_theRec);
@try
{
[self.fileContents getBytes:buffer range:recordRange]; // Problem is here - not reading in all 1000 bytes.
memccpy(p, c, kRecSize, sizeof(char));
}
@catch (NSException *ex)
{
NSLog(@"%ul beyond end of file.\n", (unsigned int)index);
NSLog(@"NSException thrown: %@\n", [ex description]);
}
}
@end
The file in question is several hundred kB long, and "index" = 1 for this debug session. Is there some way to view the buffer (contents) as a hex dump? I know what the bytes should be (I used "hexdump -Cv <filename>.dat > <filename>.txt to get the hex dump of <filename>.dat, which is what self.fileContents is loaded with in my initWithFile: method of this class.
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