I am comparing two strings using isEqual method and it is giving NO.
if ([trie.name isEqual:string]) {
isFound = YES;
break;
}
The trie.name is a string initialized using [[NSString alloc] initWithCharacters:&uchar length:ucharLen], where uchar is a unichar. The string is a constant string #"N". I have checked the hash values and both differ. I am not sure why creating a string using different initializer gives different hash for the same string value. In this case, how to check for string equality?
Please see the attached screenshot of the debug variables.
Currently, I am using the code:
NSString *string = #"Pirates";
unichar uchar = [string characterAtIndex:0];
size_t ucharLen = sizeof(uchar);
NSString *str = [[NSString alloc] initWithCharacters:&uchar length:ucharLen];
XCTAssertTrue([str isEqual:#"P"]);
If I given the length: as 1, it works properly. How to get the length of the unichar. Will it always be 1 so that I can hardcode 1 in this case?
The problem is with:
unichar uchar = [string characterAtIndex:0];
size_t ucharLen = sizeof(uchar);
NSString *str = [[NSString alloc] initWithCharacters:&uchar length:ucharLen];
You are creating a string from a single unichar which means the length needs to be 1. But the sizeof(unichar) returns 2 since unichar is a 16-bit (2-byte) value so you end up telling the string you are passing 2 characters, not 1.
So the resulting string contains two characters - the one you actually want and a second, random bit of garbage that happens to be at that memory address.
Just hardcode 1:
unichar uchar = [string characterAtIndex:0];
NSString *str = [[NSString alloc] initWithCharacters:&uchar length:1];
Related
I am trying to parse a set of words that contain -- first greek letters, then english letters. This would be easy if there was a delimiter between the sets.That is what I've built so far..
- (void)loadWordFileToArray:(NSBundle *)bundle {
NSLog(#"loadWordFileToArray");
if (bundle != nil) {
NSString *path = [bundle pathForResource:#"alfa" ofType:#"txt"];
//pull the content from the file into memory
NSData* data = [NSData dataWithContentsOfFile:path];
//convert the bytes from the file into a string
NSString* string = [[NSString alloc] initWithBytes:[data bytes]
length:[data length]
encoding:NSUTF8StringEncoding];
//split the string around newline characters to create an array
NSString* delimiter = #"\n";
incomingWords = [string componentsSeparatedByString:delimiter];
NSLog(#"incomingWords count: %lu", (unsigned long)incomingWords.count);
}
}
-(void)parseWordArray{
NSLog(#"parseWordArray");
NSString *seperator = #" = ";
int i = 0;
for (i=0; i < incomingWords.count; i++) {
NSString *incomingString = [incomingWords objectAtIndex:i];
NSScanner *scanner = [NSScanner localizedScannerWithString: incomingString];
NSString *firstString;
NSString *secondString;
NSInteger scanPosition;
[scanner scanUpToString:seperator intoString:&firstString];
scanPosition = [scanner scanLocation];
secondString = [[scanner string] substringFromIndex:scanPosition+[seperator length]];
// NSLog(#"greek: %#", firstString);
// NSLog(#"english: %#", secondString);
[outgoingWords insertObject:[NSMutableArray arrayWithObjects:#"greek", firstString, #"english",secondString,#"category", #"", nil] atIndex:0];
[englishWords insertObject:[NSMutableArray arrayWithObjects:secondString,nil] atIndex:0];
}
}
But I cannot count on there being delimiters.
I have looked at this question. I want something similar. This would be: grab the characters in the string until an english letter is found. Then take the first group to one new string, and all the characters after to a second new string.
I only have to run this a few times, so optimization is not my highest priority.. Any help would be appreciated..
EDIT:
I've changed my code as shown below to make use of NSLinguisticTagger. This works, but is this the best way? Note that the interpretation for english characters is -- for some reason "und"...
The incoming string is: άγαλμα, το statue, only the last 6 characters are in english.
int j = 0;
for (j=0; j<incomingString.length; j++) {
NSString *language = [tagger tagAtIndex:j scheme:NSLinguisticTagSchemeLanguage tokenRange:NULL sentenceRange:NULL];
if ([language isEqual: #"und"]) {
NSLog(#"j is: %i", j);
int k = 0;
for (k=0; k<j; k++) {
NSRange range = NSMakeRange (0, k);
NSString *tempString = [incomingString substringWithRange:range ];
NSLog (#"tempString: %#", tempString);
}
return;
}
NSLog (#"Language: %#", language);
}
Alright so what you could do is use NSLinguisticTagger to find out the language of the word (or letter) and if the language has changed then you know where to split the string. You can use NSLinguisticTagger like this:
NSArray *tagschemes = #[NSLinguisticTagSchemeLanguage];
NSLinguisticTagger *tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:tagschemes options: NSLinguisticTagPunctuation | NSLinguisticTaggerOmitWhitespace];
[tagger setString:#"This is my string in English."];
NSString *language = [tagger tagAtIndex:0 scheme:NSLinguisticTagSchemeLanguage tokenRange:NULL sentenceRange:NULL];
//Loop through each index of the string's characters and check the language as above.
//If it has changed then you can assume the language has changed.
Alternatively you can use NSSpellChecker's requestCheckingOfString to get teh dominant language in a range of characters:
NSSpellChecker *spellChecker = [NSSpellChecker sharedSpellChecker];
[spellChecker setAutomaticallyIdentifiesLanguages:YES];
NSString *spellCheckText = #"Guten Herr Mustermann. Dies ist ein deutscher Text. Bitte löschen Sie diesen nicht.";
[spellChecker requestCheckingOfString:spellCheckText
range:(NSRange){0, [spellCheckText length]}
types:NSTextCheckingTypeOrthography
options:nil
inSpellDocumentWithTag:0
completionHandler:^(NSInteger sequenceNumber, NSArray *results, NSOrthography *orthography, NSInteger wordCount) {
NSLog(#"dominant language = %#", orthography.dominantLanguage);
}];
This answer has information on how to detect the language of an NSString.
Allow me to introduce two good friends of mine.
NSCharacterSet and NSRegularExpression.
Along with them, normalization. (In Unicode terms)
First, you should normalize strings before analyzing them against a character set.
You will need to look at the choices, but normalizing to all composed forms is the way I would go.
This means an accented character is one instead of two or more.
It simplifies the number of things to compare.
Next, you can easily build your own NSCharacterSet objects from strings (loaded from files even) to use to test set membership.
Lastly, regular expressions can achieve the same thing with Unicode Property Names as classes or categories of characters. Regular expressions could be more terse but more expressive.
I am trying to enter a string (or a number of integers) from the command line using Objective C. These numbers are separated by a space.
Sample Input: 1 2 3 4 5
I am trying the code
char input[100] = {0};
NSString *inputString;
scanf("%s", input);
inputString = [NSString stringWithCString:input encoding:NSUTF8StringEncoding];
The resulting value of inputString is 1.
How do I get the entire value into the string ?
NSLog(#"Enter the string : ");
NSFileHandle *input = [NSFileHandle fileHandleWithStandardInput];
NSData *inputData = [NSData dataWithData:[input availableData]];
NSString *inputString = [[NSString alloc] initWithData:inputData encoding:NSUTF8StringEncoding];
inputString = [inputString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(#"%#", inputString);
Here try this more precise when talking objective C as the working language
When you use %s in scanf it truncate the input at the first space. See here:
Any number of non-whitespace characters, stopping at the first
whitespace character found. A terminating null character is
automatically added at the end of the stored sequence.
You can use this according to this source:
scanf("%[^\n]s", intpu);
You can also use gets() as an alternative.
I found a way to set a string to a char array. I use the following code:
NSString *string = [[NSString alloc] initWithFormat:#"This is a string!"];
char *c = [string UTF8String];
However, I get the warning, "Initializing 'char ' with an expresion type of 'const char' discards qualifiers.
It works fine, but I feel like there's a better way to do it, and I'd rather not have a ton of warnings. Does anyone have any suggestions?
The value returned by [NSString UTF8String] is a pointer to a constant array of chars. You cannot remove "const" directly.
If you want a non-constant array of chars you must copy the string using the method strcpy(...). You have to declare and initialize an array of chars and then copy the value of the given string inside:
NSString *string = #"This is a string";
char cString [string.length]
strcpy(cString, string.UTF8String);
NSLog(#"Copied String: %s", cString);
or if you prefer to manage the memory yourself:
NSString *string = #"This is a string";
char * cString = malloc(sizeof(char)*string.length);
strcpy(cString, string.UTF8String);
NSLog(#"Copied String: %s", cString);
free(cString);
Use const char and you can use different types of encoding also:
const char* c = [string cStringUsingEncoding:NSUTF8StringEncoding];
NSFileManager *fileMgr = [NSFileManager defaultManager];
if (![fileMgr fileExistsAtPath:pathOfDB]) {
const char *pathDB = [pathOfDB UTF8String];
I've got some trouble 'ere trying to remove the last character of an NSString.
I'm kinda newbie in Objective-C and I have no idea how to make this work.
Could you guys light me up?
NSString *newString = [oldString substringToIndex:[oldString length]-1];
Always refer to the documentation:
substringToIndex:
length
To include code relevant to your case:
NSString *str = textField.text;
NSString *truncatedString = [str substringToIndex:[str length]-1];
Try this:
s = [s substringToIndex:[s length] - 1];
NSString *string = [NSString stringWithString:#"ABCDEF"];
NSString *newString = [string substringToIndex:[string length]-1];
NSLog(#"%#",newString);
You can see = ABCDE
NSString = *string = #"abcdef";
string = [string substringToIndex:string.length-(string.length>0)];
If there is a character to delete (i.e. the length of the string is greater than 0)
(string.length>0) returns 1, thus making the code return:
string = [string substringToIndex:string.length-1];
If there is NOT a character to delete (i.e. the length of the string is NOT greater than 0)
(string.length>0) returns 0, thus making the code return:
string = [string substringToIndex:string.length-0];
which prevents crashes.
This code will just return the last character of the string and not removing it :
NSString *newString = [oldString substringToIndex:[oldString length]-1];
you may use this instead to remove the last character and retain the remaining values of a string :
str = [str substringWithRange:NSMakeRange(0,[str length] - 1)];
and also using substringToIndex to a NSString with 0 length will result to crashes.
you should add validation before doing so, like this :
if ([str length] > 0) {
str = [str substringToIndex:[s length] - 1];
}
with this, it is safe to use substring method.
NOTE : Apple will reject your application if it is vulnerable to crashes.
Simple and Best Approach
[mutableString deleteCharactersInRange:NSMakeRange([myRequestString length]-1, 1)];
I have a ascii code, for the letter 'a', and I want to get a string by its ascii code, is it possible with NSString?
This could also work:
NSString *foo = [NSString stringWithFormat:#"%c", 97];
Didn’t test it.
If you mean you have a byte that represents an ASCII-encoded character and you want to make a string out of it, NSString has an initializer just for that.
char characterCodeInASCII = 97;
NSString *stringWithAInIt = [[NSString alloc] initWithBytes:&characterCodeInASCII length:1 encoding:NSASCIIStringEncoding];