I used the localizedStringWithFormat: method on NSString class to convert a seven digit integer number to an NSString somewhere in my code and need to convert it back to an integer now.
As my App is localized for different regions with different separators after three digits (e.g. '.' in the U.S. and ',' in Germany), what's the best way to convert a localized NSString integer value to an integer?
I tried integerValue on my string as follows but it didn't work:
// Somewhere in code:
int num = 1049000;
NSString *myLocalizedNumString = [NSString localizedStringWithFormat:#"%d", num];
// myLocalizedNumString (U.S.): '1,049,000'
// myLocalizedNumString (Germany): '1.049.000'
// Somewhere else where I have a reference to my string but none to the num:
int restoredNum = [myLocalizedNumString integerValue];
// restoredNum isn't 1049000 (it's 0, the initial value)
What would be a good working way of doing it?
Despite its name NSNumberFormatter converts both ways, it is also a string parser. Using the method numberFromString after setting the number formatter’s numberStyle property to NSNumberFormatterDecimalStyle solves your problem.
The code might look as follows:
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.numberStyle = NSNumberFormatterDecimalStyle;
NSInteger restoredNum = [[formatter numberFromString:myLocalizedNumString] integerValue];
I'm having problems with converting NSNumber to string and string to NSNumber.
Here's a sample problem:
NSString *stringValue = #"9.2";
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
NSLog(#"stringvalue:%#",[[formatter numberFromString: stringValue] stringValue]);
Output will be:
stringvalue:9.199999999999999
I need to retrieve the original value, where, in the example should be 9.2.
On the contrary, when the original string is 9.4 the output is still 9.4.
Do you have any idea how to retrieve the original string value without NSNumber doing anything about it?
You are discovering that floating point numbers can't always be represented exactly. There are numerous posts about such issues.
If you need to get back to the original string, then keep the original string as your data and only convert to a number when you need to perform a calculation.
You may want to look into NSDecimalNumber. This may better fit your needs.
NSString *numStr = #"9.2";
NSDecimalNumber *decNum = [NSDecimalNumber decimalNumberWithString:numStr];
NSString *newStr = [decNum stringValue];
NSLog(#"decNum = %#, newStr = %#", decNum, newStr);
This gives 9.2 for both values.
I need to get a long value from an NSString.
For example, I have this:
NSString *test = #"5437128";
and I need :
long myLong = 5437128;
How I can get this long value from the NSString?
Thank you, it will help me!
long longVariable = [test longLongValue];
See NSString documentation..
Use the NSScanner like in the following code:
unsigned x;
[[NSScanner scannerWithString: s2] scanHexInt: &x];
when typing the scanHexInt stop at scan and see yourself which one you need - there are many possibilities to get values from strings....
You might want to use scanlonglong... having declared your variable as long
use this code :
NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
long number = [[numberFormatter numberFromString:string] longValue];
[numberFormatter release];
i use the following in case you don't want to lose the fractions value of your number
double x =[stringValue doubleValue];
instead of
double x = [stringValue longLongValue];
if we assume that we have the following string value
and we want to convert it to double we have 2 ways
NSString * stringValue = #"31.211529225111";
way #1
double x = [stringValue longLongValue];
result will be : x = 31
way #2
double x =[stringValue doubleValue];
result will be : x = 31.211529225111001
I've got a number in a NSString #"15". I want to convert this to NSUInteger, but I don't know how to do that...
NSString *str = #"15";
// Extract an integer number, returns 0 if there's no valid number at the start of the string.
NSInteger i = [str integerValue];
If you really want an NSUInteger, just cast it, but you may want to test the value beforehand.
The currently chosen answer is incorrect for NSUInteger. As Corey Floyd points out a comment on the selected answer this won't work if the value is larger than INT_MAX. A better way of doing this is to use NSNumber and then using one of the methods on NSNumber to retrieve the type you're interested in, e.g.:
NSString *str = #"15"; // Or whatever value you want
NSNumber *number = [NSNumber numberWithLongLong: str.longLongValue];
NSUInteger value = number.unsignedIntegerValue;
All these answers are wrong on a 64-bit system.
NSScanner *scanner = [NSScanner scannerWithString:#"15"];
unsigned long long ull;
if (![scanner scanUnsignedLongLong:&ull]) {
ull = 0; // Or handle failure some other way
}
return (NSUInteger)ull; // This happens to work because NSUInteger is the same as unsigned long long at the moment.
Test with 9223372036854775808, which won't fit in a signed long long.
you can try with [string longLongValue] or [string intValue]..
I want to convert a string into a double and after doing some math on it, convert it back to a string.
How do I do this in Objective-C?
Is there a way to round a double to the nearest integer too?
You can convert an NSString into a double with
double myDouble = [myString doubleValue];
Rounding to the nearest int can then be done as
int myInt = (int)(myDouble + (myDouble>0 ? 0.5 : -0.5))
I'm honestly not sure if there's a more streamlined way to convert back into a string than
NSString* myNewString = [NSString stringWithFormat:#"%d", myInt];
To really convert from a string to a number properly, you need to use an instance of NSNumberFormatter configured for the locale from which you're reading the string.
Different locales will format numbers differently. For example, in some parts of the world, COMMA is used as a decimal separator while in others it is PERIOD — and the thousands separator (when used) is reversed. Except when it's a space. Or not present at all.
It really depends on the provenance of the input. The safest thing to do is configure an NSNumberFormatter for the way your input is formatted and use -[NSFormatter numberFromString:] to get an NSNumber from it. If you want to handle conversion errors, you can use -[NSFormatter getObjectValue:forString:range:error:] instead.
Adding to olliej's answer, you can convert from an int back to a string with NSNumber's stringValue:
[[NSNumber numberWithInt:myInt] stringValue]
stringValue on an NSNumber invokes descriptionWithLocale:nil, giving you a localized string representation of value. I'm not sure if [NSString stringWithFormat:#"%d",myInt] will give you a properly localized reprsentation of myInt.
Here's a working sample of NSNumberFormatter reading localized number String (xCode 3.2.4, osX 10.6), to save others the hours I've just spent messing around. Beware: while it can handle trailing blanks such as "8,765.4 ", this cannot handle leading white space and this cannot handle stray text characters. (Bad input strings: " 8" and "8q" and "8 q".)
NSString *tempStr = #"8,765.4";
// localization allows other thousands separators, also.
NSNumberFormatter * myNumFormatter = [[NSNumberFormatter alloc] init];
[myNumFormatter setLocale:[NSLocale currentLocale]]; // happen by default?
[myNumFormatter setFormatterBehavior:NSNumberFormatterBehavior10_4];
// next line is very important!
[myNumFormatter setNumberStyle:NSNumberFormatterDecimalStyle]; // crucial
NSNumber *tempNum = [myNumFormatter numberFromString:tempStr];
NSLog(#"string '%#' gives NSNumber '%#' with intValue '%i'",
tempStr, tempNum, [tempNum intValue]);
[myNumFormatter release]; // good citizen
olliej's rounding method is wrong for negative numbers
2.4 rounded is 2 (olliej's method gets this right)
−2.4 rounded is −2 (olliej's method returns -1)
Here's an alternative
int myInt = (int)(myDouble + (myDouble>0 ? 0.5 : -0.5))
You could of course use a rounding function from math.h
// Converting String in to Double
double doubleValue = [yourString doubleValue];
// Converting Double in to String
NSString *yourString = [NSString stringWithFormat:#"%.20f", doubleValue];
// .20f takes the value up to 20 position after decimal
// Converting double to int
int intValue = (int) doubleValue;
or
int intValue = [yourString intValue];
For conversion from a number to a string, how about using the new literals syntax (XCode >= 4.4), its a little more compact.
int myInt = (int)round( [#"1.6" floatValue] );
NSString* myString = [#(myInt) description];
(Boxes it up as a NSNumber and converts to a string using the NSObjects' description method)
For rounding, you should probably use the C functions defined in math.h.
int roundedX = round(x);
Hold down Option and double click on round in Xcode and it will show you the man page with various functions for rounding different types.
This is the easiest way I know of:
float myFloat = 5.3;
NSInteger myInt = (NSInteger)myFloat;
from this example here, you can see the the conversions both ways:
NSString *str=#"5678901234567890";
long long verylong;
NSRange range;
range.length = 15;
range.location = 0;
[[NSScanner scannerWithString:[str substringWithRange:range]] scanLongLong:&verylong];
NSLog(#"long long value %lld",verylong);
convert text entered in textfield to integer
double mydouble=[_myTextfield.text doubleValue];
rounding to the nearest double
mydouble=(round(mydouble));
rounding to the nearest int(considering only positive values)
int myint=(int)(mydouble);
converting from double to string
myLabel.text=[NSString stringWithFormat:#"%f",mydouble];
or
NSString *mystring=[NSString stringWithFormat:#"%f",mydouble];
converting from int to string
myLabel.text=[NSString stringWithFormat:#"%d",myint];
or
NSString *mystring=[NSString stringWithFormat:#"%f",mydouble];
I ended up using this handy macro:
#define STRING(value) [#(value) stringValue]