Scanf'ing for a string to search for within an array object...

[MalSleek]

Basically, I'd like to ask the user for what he'd like to search for in a particular array (an address book)...

and if he types part of a NAME (ie Mark), the program will search each object in the array (ie name part of address) for that NAME and print the object in the array if it contains it.

So I'm trying to use a scanf ("%@", &theName) where name is an NSString object.

I've tried using a rangeOfString when comparing the object to the string name, but they are "incompatible data types" and the program won't function...

What NS method can I use to search for string contents within an object in an array?

Thanks -

Mal

PS: I'm on chapter 15 exercise 2 of Kochan's Objective-C book - just trying to implement some user interaction to the exercise...

[FlyingDiver]

You should be using rangeOfString (or something similar). Post the code so we can tell you what you did wrong to get that error message.

joe

[MalSleek]

 //Method I'm trying to use

-(AddressCard *) lookup: (NSString *) theName
{
	AddressCard *nextCard;
	NSRange substr;
	
	
	
	int i, elements;
	elements = [book count];
	
	for (i = 0; i<elements; ++i) {
		nextCard = [book objectAtIndex: i];
		
		substr = [nextCard rangeOfString: theName];
		
		if (substr.location != NSNotFound)
			return nextCard;
	}
	
	return nil;
}

//program - see lookup section
#import "AddressBook.h"
#import <Foundation/NSAutoreleasePool.h>

int main(int argc, char *argv[])
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	NSString *aName = @"Julia Kochan";
	NSString *aEmail = @"jewls337@axlc.com";
	NSString *bName = @"Tony Iannino";
	NSString *bEmail = @"tony.iannino@techfitness.com";
	NSString *cName = @"Stephen Kochan";
	NSString *cEmail = @"steve@kochan-wood.com";
	NSString *dName = @"Jamie Baker";
	NSString *dEmail = @"jbaker@kochan-wood.com";
	
	AddressCard *card1 = [[AddressCard alloc] init];
	AddressCard *card2 = [[AddressCard alloc] init];
	AddressCard *card3 = [[AddressCard alloc] init];
	AddressCard *card4 = [[AddressCard alloc] init];
	
	AddressBook *myBook = [AddressBook alloc];
	AddressCard *myCard;
	
	[card1 setName: aName andEmail: aEmail];
	[card2 setName: bName andEmail: bEmail];
	[card3 setName: cName andEmail: cEmail];
	[card4 setName: dName andEmail: dEmail];
	
	myBook = [myBook initWithName: @"Linda's Address Book"];
		
	[myBook addCard: card1];
	[myBook addCard: card2];
	[myBook addCard: card3];
	[myBook addCard: card4];
	
	NSString *nombre;
	
	printf("What's the info you'd like to search for?");
	scanf("%@", &nombre);
	
	[myBook lookup: nombre];
	
	if (myCard != nil)
		[myCard print];
	else
		printf ("Not found!\n");
	
	
	[myBook sort];
	[myBook list];
	
	[card1 release];
	[card2 release];
	[card3 release];
	[card4 release];
	[myBook release];
	[pool release];
	
	return 0;
	
}

[FlyingDiver]

I thought you were using the built-in AddressBook. It appears you're using a custom class. We'll need to see the code for that, but I'm 100% sure the problem is in this line:

substr = [nextCard rangeOfString: theName];

You can't call rangeOfString on a non-NSString object. You need to be doing something more like:

substr = [[nextCard name] rangeOfString: theName];

Where the name accessor in AddressBook returns an NSString containing the name field to search in.

joe

[MalSleek]

Hmm, I did try that initially and had the same problem...I changed it back to that...here's everything I have and the program generated at the bottom...

AddressCard.h

#import <Foundation/NSObject.h>
#import <Foundation/NSString.h>
#import <Foundation/NSRange.h>

@interface AddressCard: NSObject
{
NSString *name;
NSString *email;
}

-(void) setName: (NSString *) theName;
-(void) setEmail: (NSString *) theEmail;
-(void) setName: (NSString *) theName andEmail: (NSString *) theEmail;
-(NSComparisonResult) compareNames: (id) element;

-(NSString *) name;
-(NSString *) email;

-(void) dealloc;

-(void) print;

@end

AddressCard.m

#import <Foundation/NSObject.h>
#import <Foundation/NSString.h>
#import <Foundation/NSRange.h>

@interface AddressCard: NSObject
{
NSString *name;
NSString *email;
}

-(void) setName: (NSString *) theName;
-(void) setEmail: (NSString *) theEmail;
-(void) setName: (NSString *) theName andEmail: (NSString *) theEmail;
-(NSComparisonResult) compareNames: (id) element;

-(NSString *) name;
-(NSString *) email;

-(void) dealloc;

-(void) print;

@end

AddressBook.h

#import <Foundation/NSArray.h>
#import "AddressCard.h"

@interface AddressBook: NSObject
{
NSString		*bookName;
NSMutableArray	*book;
}

-(AddressBook *) initWithName: (NSString *) name;
-(void) addCard: (AddressCard *) theCard;
-(void) removeCard: (AddressCard *) theCard;
-(AddressCard *) lookup: (NSString *) theName;
-(void) sort;
-(int) entries;
-(void) list;
-(void) dealloc;

@end

AddressBook.m

#import "AddressBook.h"

@implementation AddressBook;

-(id) initWithName: (NSString *) name
{
	self = [super init];
	
	if (self) {
		bookName = [[NSString alloc] initWithString: name];
		book = [[NSMutableArray alloc] init];
	}
	
	return self;
}

-(void) addCard: (AddressCard *) theCard
{
	[book addObject: theCard];
}

-(void) removeCard: (AddressCard *) theCard
{
	[book removeObjectIdenticalTo: theCard];
}

-(void) sort
{
	[book sortUsingSelector: @selector (compareNames:)];
}

-(AddressCard *) lookup: (NSString *) theName
{
	AddressCard *nextCard;
	NSRange substr;
	
	
	
	int i, elements;
	elements = [book count];
	
	for (i = 0; i<elements; ++i) {
		nextCard = [book objectAtIndex: i];
		
		substr = [[nextCard name] rangeOfString: theName];
		
		if (substr.location != NSNotFound)
			return nextCard;
	}
	
	return nil;
}

-(int) entries
{
	[book count];
}

-(void) list
{
	int i, elements;
	AddressCard *theCard;
	
	printf("\n======== Contents of: %s =========\n", [bookName cString]);
	
	elements = [book count];
	
	for (i = 0; i < elements; ++i) {
		theCard = [book objectAtIndex: i];
		printf("%-20s %-32s\n",[[theCard name] cString], [[theCard email] cString]);
	}
	
	printf("====================================================\n\n");
}

-(void) dealloc
{
	[bookName release];
	[book release];
	[super dealloc];
}

@end

Main.m

#import "AddressBook.h"
#import <Foundation/NSAutoreleasePool.h>

int main(int argc, char *argv[])
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	NSString *aName = @"Julia Kochan";
	NSString *aEmail = @"jewls337@axlc.com";
	NSString *bName = @"Tony Iannino";
	NSString *bEmail = @"tony.iannino@techfitness.com";
	NSString *cName = @"Stephen Kochan";
	NSString *cEmail = @"steve@kochan-wood.com";
	NSString *dName = @"Jamie Baker";
	NSString *dEmail = @"jbaker@kochan-wood.com";
	
	AddressCard *card1 = [[AddressCard alloc] init];
	AddressCard *card2 = [[AddressCard alloc] init];
	AddressCard *card3 = [[AddressCard alloc] init];
	AddressCard *card4 = [[AddressCard alloc] init];
	
	AddressBook *myBook = [AddressBook alloc];
	AddressCard *myCard;
	
	[card1 setName: aName andEmail: aEmail];
	[card2 setName: bName andEmail: bEmail];
	[card3 setName: cName andEmail: cEmail];
	[card4 setName: dName andEmail: dEmail];
	
	myBook = [myBook initWithName: @"Linda's Address Book"];
		
	[myBook addCard: card1];
	[myBook addCard: card2];
	[myBook addCard: card3];
	[myBook addCard: card4];
	
	NSString *nombre;
	
	printf("What's the info you'd like to search for?");
	scanf("%@", &nombre);
	
	[myBook lookup: nombre];
	
	if (myCard != nil)
		[myCard print];
	else
		printf ("Not found!\n");
	
	
	[myBook sort];
	[myBook list];
	
	[card1 release];
	[card2 release];
	[card3 release];
	[card4 release];
	[myBook release];
	[pool release];
	
	return 0;
	
}

Program response after build

What's the info you'd like to search for?2009-04-22 22:14:11.134 Address Book[198:10b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSCFString rangeOfString:options:range:locale:]: nil argument'
2009-04-22 22:14:11.136 Address Book[198:10b] Stack: (
    2479034635,
    2415971899,
    2479034091,
    2479034154,
    2423308442,
    2423344392,
    10811,
    9246,
    8434
)

[Session started at 2009-04-22 22:14:11 -0400.]
Loading program into debugger…
GNU gdb 6.3.50-20050815 (Apple version gdb-962) (Sat Jul 26 08:14:40 UTC 2008)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-apple-darwin".Program loaded.
sharedlibrary apply-load-rules all
Attaching to program: `/Users/Mal/Desktop/Address Book/build/Debug/Address Book.app/Contents/MacOS/Address Book', process 198.
(gdb)

Most of this is from the textbook...the only part with errors are the parts I tried to create haha...could it be something to do with the myCard object? I feel like this is doing nothing...

[FlyingDiver]

Please post the contents of AddressCard.m. You posted the header file twice.

joe

[MalSleek]

AddressCard.m

#import "AddressCard.h"

@implementation AddressCard;

-(void) setName: (NSString *) theName
{
	[name release];
	name = [[NSString alloc] initWithString: theName];
}

-(void) setEmail: (NSString *) theEmail
{
	[email release];
	email= [[NSString alloc] initWithString: theEmail];
}

-(void) setName: (NSString *) theName andEmail: (NSString *) theEmail
{
	[self setName: theName];
	[self setEmail: theEmail];
}

-(NSComparisonResult) compareNames: (id) element
{
	return [name compare: [element name]];
}

-(NSString *) name
{
	return name;
}

-(NSString *) email
{
	return email;
}

-(void) dealloc
{
	[name release];
	[email release];
	[super dealloc];
}

-(void) print
{
	printf ("====================================\n");
	printf ("|                                  |\n");
	printf ("|  %-31s |\n", [name cString]);
	printf ("|  %-31s |\n", [email cString]);
	printf ("|                                  |\n");
	printf ("|                                  |\n");
	printf ("|                                  |\n");
	printf ("|       O                   O      |\n");
	printf ("====================================\n");
}

@end

ACK - sorry bout that...

[FlyingDiver]

Also, this line:

	[myBook lookup: nombre];

Needs to be:

myCard = [myBook lookup: nombre];

joe

[MalSleek]

ah ok that makes more sense-thanks...still getting same error for the program build. I changed the scanf so it's looking for %s instead of %@. There must be something wrong with the lookup method still since it's not finding entries.

Mal

[Kalimba]

I don't think you can scanf() into an NSString, and even if you can I think your code would be scanning it into a nil instance. Try scanning the user's input into a char array, then build an NSString from that if you need to. Something like this should do the trick:

    char str[256]; // accepts a string up to 255 bytes long
    scanf( "%s", str ); // get the user's input into 'str'

BTW, have you tried debugging this or are you just running it to see whether it crashes or not? I think that if you were to step through your code in the debugger, you'd quickly see what's working and what's causing problems.

[FlyingDiver]

I don't think you're actually passing in a valid NSString. Since you're using scanf, you're getting a cstring. You need to then create an NSString from that to pass into the lookup method. Try:

char name[100];
NSString *nombre;
	
printf("What's the info you'd like to search for?");
scanf("%s", &name);

nombre = [NSString stringWithCString: name encoding: NSASCIIStringEncoding];

[myBook lookup: nombre];

And use some NSLog statements to verify what you're getting at each stage.

joe

[MalSleek]

char name[100];
	NSString *nombre;
	
	printf("What's the info you'd like to search for?");
	scanf("%s", &name);
	
	nombre = [NSString stringWithCString: name encoding: NSASCIIStringEncoding];
	
	myCard = [myBook lookup: nombre];
	
	if (myCard != nil)
		[myCard print];
	else
		printf("Not found!");

Okay took your word and it works! So it looks like the problem was that I couldn't pass the scanf without the right encoding.. Thanks very much for your help.

Kalimba I haven't tried just a debug, I've always done build and run and looked for errors - thank for the advice. I just started with this a few weeks ago so there are probably quite a few obvious things I'm overlooking

Thanks again -

Mal

[parag.deshpande]

#import<Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
char word[50];
scanf("%s",&word);

NSString* word2 =[NSString stringWithCString:word encoding: NSASCIIStringEncoding];



NSLog(@"%@",word2);
[pool release];
return 0;
}