NSMutableString *a = #"Hi";
NSMutableString *b =[a stringByAppendingString:#"\n\n Hi Again"];
The above doesn't give an error but does not put "Hi Again" on the next line. Why?
EDIT2
I realised after posting, that the OP had NSString in the title but put NSMutableString in the code. I have submitted an edit to change the NSMutableString to NSString.
I will leave this as it still maybe helpful.
Well I am surprised that does not give an error, because you are giving a NSMutableString a NSString.
You need to read the Documentation on NSMutableStrings.
to give you an idea
//non mutable strings
NSString *shortGreetingString = #"Hi";
NSString *longGreetingString = #"Hi Again";
/*mutable string - is created and given a character capacity The number of characters indicated by capacity is simply a hint to increase the efficiency of data storage. The value does not limit the length of the string
*/
NSMutableString *mutableString= [NSMutableString stringWithCapacity:15];
/*The mutableString, now uses an appendFormat to construct the string
each %# in the Parameters for the appendFormat is a place holder for values of NSStrings
listed in the order you want after the comma.
Any other charactars will be included in the construction, in this case the new lines.
*/
[mutableString appendFormat:#"%#\n\n%#",shortGreetingString,longGreetingString];
NSLog (#"mutableString = %#" ,mutableString);
[pool drain];
I think this might help you. You'd rather to use '\r' instead of '\n'
I also had a similar problem and found \n works in LLDB but not in GDB
Try using NSString. You could use:
NSString *a = [NSString stringWithFormat:#"%#\n\n%#", #"Hi", #"Hello again"]
If your string is going in a UIView (e.g a UILabel), you also need to set the number of lines to 0
myView.numberOfLines=0;
Related
I am attempting to use scanf to assign a value to an NSString, as per the answers to this question by Omar. This is the code, taken straight from progrmr's answer:
char word[40];
int nChars = scanf("%39s", word); // read up to 39 chars (leave room for NUL)
NSString* word2 = [NSString stringWithBytes:word
length:nChars
encoding:NSUTF8StringEncoding];
However, I'm getting an error on the last line that makes absolutely no sense to me:
No known class method for selector 'stringWithBytes:length:encoding:'
What in the world could be causing this error?
And yes, I do have #import <Foundation/Foundation.h> at the top of the file.
NSString does not have a stringWithBytes:length:encoding: class method, but you can use
NSString* word2 = [[NSString alloc] initWithBytes:word
length:nChars
encoding:NSUTF8StringEncoding];
Note however, that scanf() returns the number of scanned items and
not the number of scanned characters. So nChars will contain 1 and not the string length, so you should set nChars = strlen(word) instead.
A simpler alternative is (as also mentioned in one answer to the linked question)
NSString* word2 = [NSString stringWithUTF8String:word];
NSString does not respond to the selector stringWithBytes:length:encoding:. You probably wanted initWithBytes:length:encoding:.
Story in short: you might want to consider a const char C-string suitable initializer for your NSString object. Also, allocate memory before sending any initializer message to the NSString object. I would expect something like:
char word[40];
int nChars = scanf("%39s", word);
NSString *word2 = [[NSString alloc] initWithCString:word encoding:NSASCIIStringEncoding];
Note that initWithCString per design only supports properly null '\0' terminated 8-bit character arrays. For unterminated bytes arrays you have initWithBytes:length:encoding: instead.
For Unicode characters you could consider initWithCharactersNoCopy:length:freeWhenDone:.
I want to get a character from somewhere inside an NSString. I want the result to be an NSString.
This is the code I use to get a single character at index it:
[[s substringToIndex:i] substringToIndex:1]
Is there a better way to do it?
This will also retrieve a character at index i as an NSString, and you're only using an NSRange struct rather than an extra NSString.
NSString * newString = [s substringWithRange:NSMakeRange(i, 1)];
If you just want to get one character from an a NSString, you can try this.
- (unichar)characterAtIndex:(NSUInteger)index;
Used like so:
NSString *originalString = #"hello";
int index = 2;
NSString *theCharacter = [NSString stringWithFormat:#"%c", [originalString characterAtIndex:index-1]];
//returns "e".
Your suggestion only works for simple characters like ASCII. NSStrings store unicode and if your character is several unichars long then you could end up with gibberish. Use
- (NSRange)rangeOfComposedCharacterSequenceAtIndex:(NSUInteger)index;
if you want to determine how many unichars your character is. I use this to step through my strings to determine where the character borders occur.
Being fully unicode able is a bit of work but depends on what languages you use. I see a lot of asian text so most characters spill over from one space and so it's work that I need to do.
NSMutableString *myString=[NSMutableString stringWithFormat:#"Malayalam"];
NSMutableString *revString=#"";
for (int i=0; i<myString.length; i++) {
revString=[NSMutableString stringWithFormat:#"%c%#",[myString characterAtIndex:i],revString];
}
NSLog(#"%#",revString);
I want the user to input a string and then assign the input to an NSString. Right now my code looks like this:
NSString *word;
scanf("%s", &word);
The scanf function reads into a C string (actually an array of char), like this:
char word[40];
int nChars = scanf("%39s", word); // read up to 39 chars (leave room for NUL)
You can convert a char array into NSString like this:
NSString* word2 = [NSString stringWithBytes:word
length:nChars
encoding:NSUTF8StringEncoding];
However scanf only works with console (command line) programs. If you're trying to get input on a Mac or iOS device then scanf is not what you want to use to get user input.
scanf does not work with any object types. If you have a C string and want to create an NSString from it, use -[NSString initWithBytes:length:encoding:].
scanf does not work with NSString as scanf doesn’t work on objects. It works only on primitive datatypes such as:
int
float
BOOL
char
What to do?
Technically a string is made up of a sequence of individual characters. So to accept string input, you can read in the sequence of characters and convert it to a string.
use:
[NSString stringWithCString:cstring encoding:1];
Here is a working example:
NSLog(#"What is the first name?");
char cstring[40];
scanf("%s", cstring);
firstName = [NSString stringWithCString:cstring encoding:1];
Here’s an explanation of the above code, comment by comment:
You declare a variable called cstring to hold 40 characters.
You then tell scanf to expect a list of characters by using the %s format specifier.
Finally, you create an NSString object from the list of characters that were read in.
Run your project; if you enter a word and hit Enter, the program should print out the same word you typed. Just make sure the word is less than 40 characters; if you enter more, you might cause the program to crash — you are welcome to test that out yourself! :]
Taken from: RW.
This is how I'd do it:
char word [40];
scanf("%s",word);
NSString * userInput = [[NSString alloc] initWithCString: word encoding: NSUTF8StringEncoding];
yes, but sscanf does, and may be a good solution for complex NSString parsing.
Maybe this will work for you because it accepts string with spaces as well.
NSLog(#"Enter The Name Of State");
char name[20];
gets(name);
NSLog(#"%s",name);
Simple Solution is
char word[40];
scanf("%39s", word);
NSString* word2 = [NSString stringWithUTF8String:word];
The NSFileHandle class is an object-oriented wrapper for a file descriptor. For files, you can read, write, and seek within the file.
NSFileHandle *inputFile = [NSFileHandle fileHandleWithStandardInput];
NSData *inputData = [inputFile availableData];
NSString *word = [[NSString alloc]initWithData:inputData encoding:NSUTF8StringEncoding];
I have an NSString and fail to apply the following statement:
NSString *myString = #"some text";
[myString stringByAppendingFormat:#"some text = %d", 3];
no log or error, the string just doesn't get changed. I already tried with NSString (as documented) and NSMutableString.
any clues most welcome.
I would suggest correcting to (documentation):
NSString *myString = #"some text";
myString = [myString stringByAppendingFormat:#" = %d", 3];
From the docs:
Returns a string made by appending to the receiver a string constructed from a given format string and the following arguments.
It's working, you're just ignoring the return value, which is the string with the appended format. (See the docs.) You can't modify an NSString — to modify an NSMutableString, use -appendFormat: instead.
Of course, in your toy example, you could shorten it to this:
NSString *myString = [NSString stringWithFormat:#"some text = %d", 3];
However, it's likely that you need to append a format string to an existing string created elsewhere. In that case, and particularly if you're appending multiple parts, it's good to think about and balance the pros and cons of using a mutable string or several immutable, autoreleased strings.
Creating strings with #"" always results in immutable strings. If you want to create a new NSMutableString do it as following.
NSMutableString *myString = [NSMutableString stringWithString:#"some text"];
[myString appendFormat:#"some text = %d", 3];
I had a similar warning message while appending a localized string. This is how I resolved it
NSString *msgBody = [msgBody stringByAppendingFormat:#"%#",NSLocalizedString(#"LOCALSTRINGMSG",#"Message Body")];
I have a fairly simple question concerning NSString however it doesn't seem to do what I want.
this is what i have
NSString *title = [NSString stringWithformat: character.name, #"is the character"];
This is a line in my parser takes the charactername and inserts in into a plist , however it doesn't insert the #"is the character" is there something I'm doing wrong?
Your code is wrong. It should be :
NSString *title
= [NSString stringWithformat:#"%# is the character", character.name];
assuming that character.name is another NSString.
Read the Formatting String Objects paragraph of the String Programming Guide for Cocoa to learn everything about formatting strings.
stringWithFormat takes a format string as the first argument so, assuming character.name is the name of your character, you need:
NSString *title = [NSString stringWithformat: #"%s is the character",
character.name];
What you have is the character name as the format string so, if it's #"Bob" then Bob is what you'll get. If it was "#Bob %s", that would work but would probably stuff up somewhere else that you display just the character name :-)
Note that you should use "%s" for a C string, I think "%#" is the correct format specifier if character.name is an NSString itself.