I'm having some trouble comparing NSStrings in Objective C. I looked at apples documentation, and it appears that there is a function that returns a boolean called isEqualToString. However, the statement never executes.
NSString* randomCombo = #"rypo";
NSFileHandle* kbd = [NSFileHandle fileHandleWithStandardInput];
NSData* inputData = [kbd availableData];
NSString* line = [[NSString alloc]initWithData : inputData encoding : NSUTF8StringEncoding];
NSLog(#"You entered: %#", line);
NSLog(#"The string to match is: %#", randomCombo);
if([line isEqualToString : randomCombo]){
NSLog(#"you win.");
}
Do I need to encode the NSString, randomCombo? Can anybody help me figure out what the problem is here?
When you use return to end your input, there's a newline character appended to the string which the other string doesn't have.
You need to either terminate input using control-D, which just closes the pipe without starting a new line, or trim the '\n' off of the string afterwards.
Related
I am a beginner of learning how to code and I want to write a string coder. By string coder, I mean if we input the word "abc", the output is "cde". That is, every character move to plus 2.
I'm able to convert a single character, for example: input "a" -> output "c".
But I'm not sure how to input a word instead of a character.
char passWord[40];
NSLog(#" Plz enter the password");
scanf("%s",passWord);
NSString *tempCode = [NSString stringWithCString:passWord encoding:1];
//NSLog(#"test %#", tempCode);
int decode, asciiCode = [tempCode characterAtIndex:0];
//NSLog(#"test %d", asciiCode);
decode = asciiCode + 2;
NSString *decodeNum = [NSString stringWithFormat:#"%c", decode];
NSLog(#"%#", decodeNum);
Could anyone give some advise please.
In my iOS app I am parsing XML (with a help of third-party-library) and have a problem with extra whitespaces/newLines at the beginning/end of the strings. Initial string, that return this third-party-library, it's a C++ std::wstring that I convert to NSString (the encoding should be right as the content of new NSString is equal to proper part of my XML-file). After the trim length of "empty" elements (that contain only whitespaces and new lines) doesn't become zero but change it's value by half.
The code is below....
std::wstring val;
NSString *initial = [[NSString alloc] initWithBytes:val.data() length:sizeof (wchar_t)*val.size() encoding:NSUTF16LittleEndianStringEncoding];
NSString *trimmed = [initial stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
If try to output like NSLog(#"bybyby'%#'bebebe", trimmed); 'bebebe have never displayed. Looks like that there are left some new lines, whitespaces that can't be detected.
wchar_t is a 32-bit integer (on iOS and OS X), therefore you must use NSUTF32LittleEndianStringEncoding for the conversion to NSString.
Example:
std::wstring val (L" Hello World ");
NSString *initial = [[NSString alloc] initWithBytes:val.data() length:sizeof (wchar_t)*val.size() encoding:NSUTF32LittleEndianStringEncoding];
NSString *trimmed = [initial stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(#"'%#'", trimmed);
// Output: 'Hello World'
What probably happened in your case (with NSUTF16LittleEndianStringEncoding)
is that every second character in the initial string is a NUL character,
which acts as a terminator when printed.
Im trying to send ascii encoded message to a server. My problem is coming in when I try to append the carriage return to the string
-(void)button2Pressed
{
NSMutableString *mutableString = [NSMutableString stringWithString:#"h323name get"];
[self sendStringCommand:mutableString];
}
-(void)sendStringCommand:(NSMutableString*)string
{
[string appendString:#"\\r"];
NSLog(#"string %# wtf",[string dataUsingEncoding:NSASCIIStringEncoding]);
NSData * testData = [[NSData alloc]initWithBytes:[string dataUsingEncoding:NSASCIIStringEncoding] length:sizeof([string dataUsingEncoding:NSASCIIStringEncoding])];
[socket writeData:testData withTimeout:20 tag:1];
}
currently this outputs this:
string <68333233 6e616d65 20676574 5c72> wtf
which should be
string <68333233 6e616d65 20676574 0d> wtf
Just plain /r did a new line hence the wtf characters after the data in the nslog
You have too many backslashes. Try this:
[string appendString:#"\r"];
Also, your creation of testData is completely wrong. The way you are creating testData is passing a pointer to an NSData object as the "bytes" parameter, and passing the size of a pointer to an NSData as the "length" parameter. You should just do this:
NSData *testData = [string dataUsingEncoding:NSASCIIStringEncoding];
Why does the following code produce the logging at the bottom ?
Here is the anomaly- my second NSLog should print the chrStr but produces nothing, empty, which is verified by this debug command:
(gdb) po chrStr
object returns empty description
However, the third NSString where I re-convert the NSString back to NSData object DOES display the the data, the same value as in the first NSLog, as it should. This would indicate to me that chrStr must have actual contents. But it seems not to be so from the NSLOG or the po command. Why ?
NSString *login;
NSString *pass;
// Purpose: NSString *loginString = [NSString stringWithFormat:#"\000%#\000%#", login, pass];
login = #"Loginname"; // text string1
pass = #"Password"; // text string2
// convert text strings to data objects
NSData *subData1 = [login dataUsingEncoding:NSUTF8StringEncoding];
NSData *subData2 = [pass dataUsingEncoding:NSUTF8StringEncoding];
// embed a NULL into new NSData object
NSMutableData *data = [NSMutableData data];
unsigned char zeroByte = 0;
[data appendBytes:&zeroByte length:1];
// append string1, NULL, string2 to data object
[data appendData:subData1];
[data appendBytes:&zeroByte length:1];
[data appendData:subData2];
NSLog(#"1.NSData: %#", data); // print data object
// create a character string from data object
NSString *chrStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"2.NSString: %#", chrStr); // print character string
// create data object from string object
NSData *chrData = [chrStr dataUsingEncoding:NSUTF8StringEncoding];
NSLog(#"3.NSDATA: %#", chrData); // print data object
Produces:
[1071:207] 1.NSData: 004c6f67 696e6e61 6d650050 61737377 6f7264
[1071:207] 2.NSString:
[1071:207] 3.NSDATA: 004c6f67 696e6e61 6d650050 61737377 6f7264
This is a real mystery to me. If chrStr is empty then 3-NSDATA could not display its info, but it does !
What am I trying to accomplish ? Well, check my very first comment line: // purpose:
That line when uncommented produces a warning, even though it actually works, so I was trying to do it another way that allowed me to have a clean compile. If you see a better way to accomplish that objective, I all eyes and ears. But please don't dwell on why that #"\000%#\000%#" string is necessary, start out accepting that it is. Thanks.
In C (and therefore objective-c), a null byte is used to represent the end of a string. When you create the string object, it takes all of the data you have given it without parsing, which is why you can convert it back to data successfully. However, when you display the string, the system reads the string up to the first null byte, which is the first byte. Therefore, the string contains data, but any system functions which read byte by byte instead of using the strings returned length will think it is empty. When you work with non-displayable characters, you should try to use data objects over string objects as often as possible.
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];