Is there a way in objectiveC to read a string with multiple lines from user input in the console?
I'm making a simple console app in Xcode, which i want people to be able to paste SQL queries which may be in few lines.
Currently i'm using:
char strIn[512];
NSMutableString* str;
scanf("%[^\n]", strIn);
str = [NSString stringWithUTF8String:strIn];
NSLog(#"\n%#",str);
But this only gets the first line.
Remember - this is not about reading from file, but only from the console.
thanks.
The following code should help you to get started. It reads from standard input and collects the input lines in the inputString variable, until a semi-colon is found.
NSFileHandle *inputFile = [NSFileHandle fileHandleWithStandardInput];
NSMutableString *inputString = [NSMutableString string];
do {
// Read from stdin, check for EOF:
NSData *data = [inputFile availableData];
if ([data length] == 0) {
NSLog(#"EOF");
break;
}
// Convert to NSString, replace newlines by spaces, append to current input:
NSMutableString *tmp = [[NSMutableString alloc] initWithData:data encoding:NSUTF8StringEncoding];
[tmp replaceOccurrencesOfString:#"\n" withString:#" " options:0 range:NSMakeRange(0, [tmp length])];
[inputString appendString:tmp];
// Check for semi-colon:
} while ([inputString rangeOfString:#";"].location == NSNotFound);
NSLog(#"input=%#", inputString);
(Note that this sample code simple checks for a semi-colon somewhere in the input. It does not check if the semi-colon is e.g. embedded in a string.)
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 have 1 Hex file, i want to read this file and parse it to NSString.
I used this code to read hex file but it only prinf hex code in console:
-(void)readHexfile
{
NSData *data = [NSData dataWithContentsOfFile:#"path file"];
NSLog(#"Patch File: %#",data);
}
Do you have any suggestions? Thanks in advance
Use stringWithContentsOfFile:encoding:error: instead of dataWithContentsOfFile to read it as NSString.
There is no such a thing like a "hex file". Hex, or hexadecimal, is a numerical system that is quite suitable to display binary data in octets (8-bit bytes) in some way suitable for humans.
What you currently do is displaying the description of the NSData object onth the console in hex.
Some quick and dirty hack could be just to use the description of the NSData.
NSString *hexString = [data description];
This will create some overhead that you could strip of using string manipulation methods.
There are smater ways that may require more work.
On the contrary, if you are not interested in a hex representation then use stringWithContentsOfFile to read the file directly into an NSString object. You can then apply various encodings depending on how your file is actually encoded.
You'd read that using a NSScanner (convert your data to a string first using [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] (assuming your text is pure ASCII or UTF-8) or read it directly using +[NSString stringWithContentsOfFile:encoding:error:]). See also the String Programming Guide on how to use scanners.
Edit: So it seems you want to read a file with null-terminated strings. A naive and inefficient way to do that would be:
NSData *data = [NSData dataWithContentsOfFile:#"file.path"];
NSMutableArray *strings = [NSMutableArray array];
const char *rawData = [data bytes];
NSUInteger dataLength = [data length];
NSMutableData *currentString = [NSMutableData data];
for (NSUInteger i = 0; i < dataLength; i++) {
if (rawData[i] == 0) {
if ([currentString length] > 0) {
[strings addObject:[[[NSString alloc] initWithData:currentString encoding:NSUTF8StringEncoding] autorelease]];
}
[currentString release];
currentString = [NSMutableData data];
} else {
[currentString appendBytes:&rawData[i] length:1];
}
}
// Handle the last string if it wasn't null-terminated.
if ([currentString length] > 0) {
[strings addObject:[[[NSString alloc] initWithData:currentString encoding:NSUTF8StringEncoding] autorelease]];
}
// "strings" now is a list of strings.
I have a NSString category I am working on to perform character substitution similar to PHP's strtr. This method takes a string and replaces every occurrence of each character in fromString and replaces it with the character in toString with the same index. I have a working method but it is not very performant and would like to make it quicker and able to handle megabytes of data.
Edit (for clarity):
stringByReplacingOccurrencesOfString:withString:options:range: will not work. I have to take a string like "ABC" and after replacing "A" with "B" and "B" with "A" end up with "BAC". Successive invocations of stringByReplacingOccurrencesOfString:withString:options:range: would make a string like "AAC" which would be incorrect.
Suggestions would be great, sample code would be even better!
Code:
- (NSString *)stringBySubstitutingCharactersFromString:(NSString *)fromString
toString:(NSString *)toString;
{
NSMutableString *substitutedString = [self mutableCopy];
NSString *aCharacterString;
NSUInteger characterIndex
, stringLength = substitutedString.length;
for (NSUInteger i = 0; i < stringLength; ++i) {
aCharacterString = [NSString stringWithFormat: #"%C", [substitutedString characterAtIndex:i]];
characterIndex = [fromString rangeOfString:aCharacterString].location;
if (characterIndex == NSNotFound) continue;
[substitutedString replaceCharactersInRange:NSMakeRange(i, 1)
withString:[NSString stringWithFormat:#"%C", [toString characterAtIndex:characterIndex]]];
}
return substitutedString;
}
Also this code is executed after every change to text in a text view. It is passed the entire string every time. I know that there is a better way to do it, but I do not know how. Any suggestions for this would be most certainly appreciated!
You can make that kind of string substitution with NSRegularExpression either modifying an mutable string or creating a new immutable string. It will work with any two strings to substitute (even if they are more than one symbol) but you will need to escape any character that means something in a regular expression (like \ [ ( . * ? + etc).
The pattern finds either of the two substrings with the optional "anything" between and than replaces them with the two substrings with each other preserving the optional string between them.
// These string can be of any length
NSString *firstString = #"Axa";
NSString *secondString = #"By";
// Escaping of characters used in regular expressions has NOT been done here
NSString *pattern = [NSString stringWithFormat:#"(%#|%#)(.*?)(%#|%#)", firstString, secondString, firstString, secondString];
NSString *string = #"AxaByCAxaCBy";
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern
options:NSRegularExpressionCaseInsensitive
error:&error];
if (error) {
// Insert error handling here...
}
NSString *modifiedString = [regex stringByReplacingMatchesInString:string
options:0
range:NSMakeRange(0, [string length])
withTemplate:#"$3$2$1"];
NSLog(#"Before:\t%#", string); // AxaByCAxaCBy
NSLog(#"After: \t%#", modifiedString); // ByAxaCByCAxa
I need to write several line to a file. How can I move to the next line so that the file content is not overwritten each time? I am using a for loop with the following code in it
[anNSString writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:NULL];
The NSString. anNSString is reinitialized during each loop. SO i need to keep adding to the file path each during each loop.
Thanks
I feel like the accepted answer is not correct since it didn't answer the original question. To solve the original question you should use an NSOutputStream it makes appending content to an existing file an easy task:
NSString *myString = #"Text to append!"; // don't forget to add linebreaks if needed (\r\n)
NSOutputStream *stream = [[NSOutputStream alloc] initToFileAtPath:filePath append:YES];
[stream open];
NSData *strData = [myString dataUsingEncoding:NSUTF8StringEncoding];
[stream write:(uint8_t *)[strData bytes] maxLength:[strData length]];
[stream close];
You just write it out all at once, rather than attempting to write it incrementally. -[NSString writeToFile:atomically:encoding:error] will just overwrite the file each time - it does not append.
Here's an illustration:
NSMutableString * str = [NSMutableString new];
// > anNSString is reinitialized during each loop.
for ( expr ) {
NSString * anNSString = ...;
// > SO i need to keep adding to the file path each during each loop.
[str appendString:anNSString];
}
NSError * outError(0);
BOOL success = [str writeToFile:path
atomically:YES
encoding:NSUTF8StringEncoding
error:&outError];
[str release];
...
If you need to write to a new line each time, start with what is in #justin's answer, but add [str appendString:#"\r\n"]; wherever you need new lines.
NSMutableString * str = [NSMutableString new];
// > anNSString is reinitialized during each loop.
for ( expr ) {
NSString * anNSString = ...;
// > SO i need to keep adding to the file path each during each loop.
[str appendString:anNSString];
[str appendString:#"\r\n"]; //****** THIS IS THE NEW LINE ******
}
NSError * outError(0);
BOOL success = [str writeToFile:path
atomically:YES
encoding:NSUTF8StringEncoding
error:&outError];
[str release];
...
With this code, each anNSString will be on it's own line in the text file.
I'm trying to use the BEncoding ObjC class to decode a .torrent file.
NSData *rawdata = [NSData dataWithContentsOfFile:#"/path/to/the.torrent"];
NSData *torrent = [BEncoding objectFromEncodedData:rawdata];
When I NSLog torrent I get the following:
{
announce = <68747470 3a2f2f74 6f727265 6e742e75 62756e74 752e636f 6d3a3639 36392f61 6e6e6f75 6e6365>;
comment = <5562756e 74752043 44207265 6c656173 65732e75 62756e74 752e636f 6d>;
"creation date" = 1225365524;
info = {
length = 732766208;
name = <7562756e 74752d38 2e31302d 6465736b 746f702d 69333836 2e69736f>;
"piece length" = 524288;
....
How do I convert the name into a NSString? I have tried..
NSData *info = [torrent valueForKey:#"info"];
NSData *name = [info valueForKey:#"name"];
unsigned char aBuffer[[name length]];
[name getBytes:aBuffer length:[name length]];
NSLog(#"File name: %s", aBuffer);
..which retrives the data, but seems to have additional unicode rubbish after it:
File name: ubuntu-8.10-desktop-i386.iso)
I have also tried (from here)..
NSString *secondtry = [NSString stringWithCharacters:[name bytes] length:[name length] / sizeof(unichar)];
..but this seems to return a bunch of random characters:
扵湵畴㠭ㄮⴰ敤歳潴⵰㍩㘸椮潳
The fact the first way (as mentioned in the Apple documentation) returns most of the data correctly, with some additional bytes makes me think it might be an error in the BEncoding library.. but my lack of knowledge about ObjC is more likely to be at fault..
That's an important point that should be re-emphasized I think. It turns out that,
NSString *content = [NSString stringWithUTF8String:[responseData bytes]];
is not the same as,
NSString *content = [[NSString alloc] initWithBytes:[responseData bytes]
length:[responseData length] encoding: NSUTF8StringEncoding];
the first expects a NULL terminated byte string, the second doesn't. In the above two cases content will be NULL in the first example if the byte string isn't correctly terminated.
How about
NSString *content = [[[NSString alloc] initWithData:myData
encoding:NSUTF8StringEncoding] autorelease];
NSData *torrent = [BEncoding objectFromEncodedData:rawdata];
When I NSLog torrent I get the following:
{
⋮
}
That would be an NSDictionary, then, not an NSData.
unsigned char aBuffer[[name length]];
[name getBytes:aBuffer length:[name length]];
NSLog(#"File name: %s", aBuffer);
..which retrives the data, but seems to have additional unicode rubbish after it:
File name: ubuntu-8.10-desktop-i386.iso)
No, it retrieved the filename just fine; you simply printed it incorrectly. %s takes a C string, which is null-terminated; the bytes of a data object are not null-terminated (they are just bytes, not necessarily characters in any encoding, and 0—which is null as a character—is a perfectly valid byte). You would have to allocate one more character, and set the last one in the array to 0:
size_t length = [name length] + 1;
unsigned char aBuffer[length];
[name getBytes:aBuffer length:length];
aBuffer[length - 1] = 0;
NSLog(#"File name: %s", aBuffer);
But null-terminating the data in an NSData object is wrong (except when you really do need a C string). I'll get to the right way in a moment.
I have also tried […]..
NSString *secondtry = [NSString stringWithCharacters:[name bytes] length:[name length] / sizeof(unichar)];
..but this seems to return random Chinese characters:
扵湵畴㠭ㄮⴰ敤歳潴⵰㍩㘸椮潳
That's because your bytes are UTF-8, which encodes one character in (usually) one byte.
unichar is, and stringWithCharacters:length: accepts, UTF-16. In that encoding, one character is (usually) two bytes. (Hence the division by sizeof(unichar): it divides the number of bytes by 2 to get the number of characters.)
So you said “here's some UTF-16 data”, and it went and made characters from every two bytes; each pair of bytes was supposed to be two characters, not one, so you got garbage (which turned out to be mostly CJK ideographs).
You answered your own question pretty well, except that stringWithUTF8String: is simpler than stringWithCString:encoding: for UTF-8-encoded strings.
However, when you have the length (as you do when you have an NSData), it is even easier—and more proper—to use initWithBytes:length:encoding:. It's easier because it does not require null-terminated data; it simply uses the length you already have. (Don't forget to release or autorelease it.)
A nice quick and dirty approach is to use NSString's stringWithFormat initializer to help you out. One of the less-often used features of string formatting is the ability to specify a mximum string length when outputting a string. Using this handy feature allows you to convert NSData into a string pretty easily:
NSData *myData = [self getDataFromSomewhere];
NSString *string = [NSString stringWithFormat:#"%.*s", [myData length], [myData bytes]];
If you want to output it to the log, it can be even easier:
NSLog(#"my Data: %.*s", [myData length], [myData bytes]);
Aha, the NSString method stringWithCString works correctly:
With the bencoding.h/.m files added to your project, the complete .m file:
#import <Foundation/Foundation.h>
#import "BEncoding.h"
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
// Read raw file, and de-bencode
NSData *rawdata = [NSData dataWithContentsOfFile:#"/path/to/a.torrent"];
NSData *torrent = [BEncoding objectFromEncodedData:rawdata];
// Get the file name
NSData *infoData = [torrent valueForKey:#"info"];
NSData *nameData = [infoData valueForKey:#"name"];
NSString *filename = [NSString stringWithCString:[nameData bytes] encoding:NSUTF8StringEncoding];
NSLog(#"%#", filename);
[pool drain];
return 0;
}
..and the output:
ubuntu-8.10-desktop-i386.iso
In cases where I don't have control over the data being transformed into a string, such as reading from the network, I prefer to use NSString -initWithBytes:length:encoding: so that I'm not dependent upon having a NULL terminated string in order to get defined results. Note that Apple's documentation says if cString is not a NULL terminated string, that the results are undefined.
Use a category on NSData:
NSData+NSString.h
#interface NSData (NSString)
- (NSString *)toString;
#end
NSData+NSString.m
#import "NSData+NSString.h"
#implementation NSData (NSString)
- (NSString *)toString
{
Byte *dataPointer = (Byte *)[self bytes];
NSMutableString *result = [NSMutableString stringWithCapacity:0];
NSUInteger index;
for (index = 0; index < [self length]; index++)
{
[result appendFormat:#"0x%02x,", dataPointer[index]];
}
return result;
}
#end
Then just NSLog(#"Data is %#", [nsData toString])"
You can try this. Fine with me.
DLog(#"responeData: %#", [[[NSString alloc] initWithBytes:[data bytes] length:[data length] encoding:NSASCIIStringEncoding] autorelease]);
Sometimes you need to create Base64 encoded string from NSData. For instance, when you create a e-mail MIME. In this case use the following:
#import "NSData+Base64.h"
NSString *string = [data base64EncodedString];
This will work.
NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];