How would I convert a pid_t instance into a string instance? I know that a pid_t is nothing more than a signed integer, and yet I can't do something like:
# suppose appID is already an instance of pid_t
NSString *appStringID = [NSString stringWithFormat:#"%#", appID];
Why does this bring up an error?
As a signed integer, it's just a formatting issue with your NSString:
do this instead:
NSString *appStringID = [NSString stringWithFormat:#"%ld", (long)appID];
A format string of "%#" implies that you're passing another NSString object in, which an integer (a raw C type) is not.
Related
Hi I got an information that NSString value is immutable and cannot be changed once it is provided a value.
But I have created and tested the following code:
NSString *str=[[NSString alloc] initWithString:#"Hello"];
NSLog(#"\n\nstr = %#",str);
str=#"asdasd";
NSLog(#"\n\n new str = %#",str);
and this gives "Hello" as first str value and "asdasd" as second str value. If it is so what is the relevance of calling NSString immutable?Thanks in advance.
What you're doing on the third line is just creating a new string and pointing it with the str variable. You didn't change the original string, but rather made the variable point to a new one.
NSString is immutable. You cannot mutate it. Your confusion arises from the fact that your variable (pointer) is not const.
All you're doing is reassigning the pointer to a different immutable string.
If you were to attempt to append a string to either, then an error would ensue. This, specifically, is "…the relevance of calling NSString immutable". You should interpret this as the string instance may not be mutated, even though the variable you have declared may be assigned another NSString instance because it is not const.
You can make both the pointer const and the string immutable like so:
NSString * const aStr = #"aStr";
You're confusing an immutable object and a constant pointer (plus you're leaking memory). Here you don't really change the NSString instance (that is, the object itself), but just a pointer to it. The point is that you can assign different instances of an NSString to the same variable, it won't change the internal contents of the object, nor would it make it respond to NSMutableString's mutation messages such as appendString etc.
Use this will sol your problem...
NSString *str=[NSString stringWithFormat:#"Hello"];
NSLog(#"\n\nstr = %#",str);
str = nil;
str=#"asdasd";
NSLog(#"\n\n new str = %#",str);
This some basic that you should know..
NSString *s1 = #"string1";
NSString *s2 = [[NSString alloc] initWithString:#"string2"];
NSString *s3 = [NSString stringWithFormat:#"string3"];
s1 in this case is a pointer to a constant string. s2 and s3 both point to new strings that you've created, but s2 has been retained for you, and s3 has been autoreleased. If you just need a temporary object, the autoreleased object s3 or the constant object s1 are good choices. If you need to keep the string around, you should use s2 (actually now that I think about it s1 will work in this case too - it's not really idiomatic, though).
You can make s1 or s3 equivalent to s2 by sending them a retain message. You could also turn s2 into an equivalent object by sending it an autorelease message.
How to convert a CGPDFStringRef to unicode char? I have used CGPDFStringCopyTextString to get the string and then [string characterAtIndex:i] to cast to unichar, is this the right way? or is there any way to get the bytes of the string and convert to unicode directly?
Need some guidance here.
NSString is capable of handling of unicode characters itself, you just need to convert the CGPDFString to NSString and further you can use it as follows:
NSString *tempStr = (NSString *)CGPDFStringCopyTextString(objectString);
although UPT's answer is correct, it will produce a memory leak
from the documentation:
CGPDFStringCopyTextString
"...You are responsible for releasing this object."
the correct way to do this would be:
CFStringRef _res = CGPDFStringCopyTextString(pdfString);
NSString *result = [NSString stringWithString:(__bridge NSString *)_res];
CFRelease(_res);
It's not a bad idea, even if you can access the CGPDFString directly using CGPDFStringGetBytePtr. You will also need CGPDFStringGetLength to get the string length, as it may not be null-terminated.
See the documentation for more info
I m having some issues here.. I am using the following code to generate the uuid in mine application.
- (NSString *)GetUUID
{
CFUUIDRef theUUID = CFUUIDCreate(NULL);
CFStringRef string = CFUUIDCreateString(NULL, theUUID);
CFRelease(theUUID);
return [(NSString *)string autorelease];
}
This code returns a NSString object back. Now I want to store the generated UUID as unsigned int. Any suggestions please how can i do it here. Thanks.
According to the Wikipedia page, UUIDs are 128 bits long. The largest int value you'll be able to work with is 64 bits. Therefore, I'd says you can't store it in an int because there simply isn't room.
Convert UUID to String using .UUIDString
Take string's .hash property.
Cast to int.
int numericFormUUID = (int)UUIDString.hash;
Note: collision is possible, as always, with hashing. Two users could end up with the same value here, whereas UUID is guaranteed unique.
I'm trying to extract a string (which contains an integer) from an array and then use it as an int in a function. I'm trying to convert it to a int using intValue.
Here's the code I've been trying.
NSArray *_returnedArguments = [serverOutput componentsSeparatedByString:#":"];
[_appDelegate loggedIn:usernameField.text:passwordField.text:(int)[[_returnedArguments objectAtIndex:2] intValue]];
I get this error:
passing argument 3 of 'loggedIn:::' makes pointer from integer
without a cast
What's wrong?
I really don't know what was so hard about this question, but I managed to do it this way:
[myStringContainingInt intValue];
It should be noted that you can also do:
myStringContainingInt.intValue;
You can just convert the string like that [str intValue] or [str integerValue]
integerValue
Returns the NSInteger value of the receiver’s text.
(NSInteger)integerValue
Return Value
The NSInteger value of the receiver’s text, assuming a decimal representation and skipping whitespace at the beginning of the string. Returns 0 if the receiver doesn’t begin with a valid decimal text representation of a number.
for more information refer here
NSArray *_returnedArguments = [serverOutput componentsSeparatedByString:#":"];
_returnedArguments is an array of NSStrings which the UITextField text property is expecting. No need to convert.
Syntax error:
[_appDelegate loggedIn:usernameField.text:passwordField.text:(int)[[_returnedArguments objectAtIndex:2] intValue]];
If your _appDelegate has a passwordField property, then you can set the text using the following
[[_appDelegate passwordField] setText:[_returnedArguments objectAtIndex:2]];
Basically, the third parameter in loggedIn should not be an integer, it should be an object of some kind, but we can't know for sure because you did not name the parameters in the method call. Provide the method signature so we can see for sure. Perhaps it takes an NSNumber or something.
Keep in mind that international users may be using a decimal separator other than . in which case values can get mixed up or just become nil when using intValue on a string.
For example, in the UK 1.23 is written 1,23, so the number 1.777 would be input by user as 1,777, which, as .intValue, will be 1777 not 1 (truncated).
I've made a macro that will convert input text to an NSNumber based on a locale argument which can be nil (if nil it uses device current locale).
#define stringToNumber(__string, __nullable_locale) (\
(^NSNumber *(void){\
NSLocale *__locale = __nullable_locale;\
if (!__locale) {\
__locale = [NSLocale currentLocale];\
}\
NSString *__string_copy = [__string stringByReplacingOccurrencesOfString:__locale.groupingSeparator withString:#""];\
__string_copy = [__string_copy stringByReplacingOccurrencesOfString:__locale.decimalSeparator withString:#"."];\
return #([__string_copy doubleValue]);\
})()\
)
If I understood you correctly, you need to convert your NSString to int? Try this peace of code:
NSString *stringWithNumberInside = [_returnedArguments objectAtIndex:2];
int number;
sscanf([stringWithNumberInside UTF8String], "%x", &flags);
I have a string value where it contains comma. Ex:- 1,234. I want to get the value of the string where i need only 1234. Can you please help me...
Instead of manually stripping out the commas, it might be more elegant (and less error-prone if you support different locales) to use an NSNumberFormatter to convert the string to a number.
NSString *myString = "1,234";
NSString *resultString = [myString stringByReplacingOccurrencesOfString:#"," withString:#""];
If you want to strip the comma then: -
NSString *string = #"1,234";
string = [string stringByReplacingOccurrencesOfString:#"," withString:#""];
This should return you a string with just 1234 in it.
By 'getting the value' do you mean, converting this to a NSNumber object? If so use this
NSNumber *numberFromString = [NSNumber numberWithInteger:[string integerValue]];
I don't know that framework/language, but if an integer converter won't work, then strip out the commas by replacing them with null from the string and then convert to an integer.