How can I have a two-digit integer in a a string, even if the integer is less than 10?
[NSString stringWithFormat:#"%d", 1] //should be #"01"
I believe that the stringWithFormat specifiers are the standard IEEE printf specifiers. Have you tried
[NSString stringWithFormat:#"%02d", 1];
Use the format string %02d. This specifies to format an integer with a minimum field-width of 2 characters and to pad the formatted values with 0 to meet that width. See man fprintf for all the gory details of format specifiers.
If you are formatting numbers for presentation to the user, though, you should really be using NSNumberFormatter. Different locales have wildly different expectations about how numbers should be formatted.
[NSString stringWithFormat:#"%00.02d", intValue]
This help me to convert 1 to 01.
Related
Is there a custom or standard library that I can use with objective c to convert a decimal floating point value into Hexadecimal, Binary and Octal NSStrings?
I've been looking around a lot but can only find how to convert the other direction (from everything else into decimal), by using: double result = (double)strtoll(myHexString.UTF8String, NULL,16)
As for octal and hex, you can exploit the fact that you can format numbers in hex and octal using the %x and %o specifiers:
NSString* str=[NSString stringWithFormat: #"Hex: %x Octal: %o",14,14];
But this only for the integral part, so you can use integers.If you want also the decimal part, to obtain fixed points you need to implement the algorithm, same for binary.
In order to complement the previous answer, the format specifier %x allows to treat integer value only.
If you get a decimal value greater than the max integer value you can use long long to cast your double value by this way: NSString * hexString = [NSString stringWithFormat:#"%llx", (long long)doubleValue];
I have a situation where I have lots of different double values, for example 1.00, 0.25 and 2.50. I would like to round these doubles so that they become 1, 0.25 and 2.5; in other words I want to remove any trailing 0's. Is there a way to do this?
At the moment I have been using %.2f, and I'm wondering if I can make use of this but adapt it in some way. Please can someone help me out?
As long as you're talking only about display, this is quite easy. The format specifier you want is %g:
The double argument shall be converted in the style f or e (or in the style F or E in the case of a G conversion specifier), with the precision specifying the number of significant digits [...] Trailing zeros shall be removed from the fractional portion of the result[...]
double twopointfive = 2.500;
double onepointzero = 1.0;
double pointtwofive = .25000000000;
NSLog(#"%g %f", twopointfive, twopointfive);
NSLog(#"%g %f", onepointzero, onepointzero);
NSLog(#"%g %f", pointtwofive, pointtwofive);
2011-12-06 21:27:59.180 TrailingZeroes[39506:903] 2.5 2.500000
2011-12-06 21:27:59.184 TrailingZeroes[39506:903] 1 1.000000
2011-12-06 21:27:59.185 TrailingZeroes[39506:903] 0.25 0.250000
The same format specifier can be used with an NSNumberFormatter, which will also give you some control over significant digits.
The trailing zeroes can't be removed from the way the number is stored in memory, of course.
I believe you want the %g format specifier to redact trailing zeros.
Not really rounding, but have you tried just %f it should only show the number of digits required rather then padding out the number.
My answer above is wrong, %g as others has stated is the right way to go.
The documentation for string formatters should help too. http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265
Here is a list of all the format specifiers that you can use...
%# Object
%d, %i signed int
%u unsigned int
%f float/double
%x, %X hexadecimal int
%o octal int
%zu size_t
%p pointer
%e float/double (in scientific notation)
%g float/double (as %f or %e, depending on value)
%s C string (bytes)
%S C string (unichar)
%.*s Pascal string (requires two arguments, pass pstr[0] as the first, pstr+1 as the second)
%c character
%C unichar
%lld long long
%llu unsigned long long
%Lf long double
I have a list of unicode char "codes" that I'd like to print using \u escape sequence (e.g. \ue415), as soon as I try to compose it with something like this:
// charCode comes as NSString object from PList
NSString *str = [NSString stringWithFormat:#"\u%#", charCode];
the compiler warns me about incomplete character code. Can anyone help me with this trivial task?
I think you can't do that the way you're trying - \uxxx escape sequence is used to indicate that a constant is a unicode character - and that conversion is processed at compile-time.
What you need is to convert your charCode to an integer number and use that value as format parameter:
unichar codeValue = (unichar) strtol([charCode UTF8String], NULL, 16);
NSString *str = [NSString stringWithFormat:#"%C", charCode];
NSLog(#"Character with code \\u%# is %C", charCode, codeValue);
Sorry, that nust not be the best way to get int value from HEX representation, but that's the 1st that came to mind
Edit: It appears that NSScanner class can scan NSString for number in hex representation:
unichar codeValue;
[[NSScanner scannerWithString:charCode] scanHexInt:&codeValue];
...
Beware that not all characters can be encoded in UTF-8. I had a bug yesterday where some Korean characters were failing to be encoded in UTF-8 properly.
My solution was to change the format string from %s to %# and avoid the re-encoding issue, although this may not work for you.
Based on codes from #Vladimir, this works for me:
NSUInteger codeValue;
[[NSScanner scannerWithString:#"0xf8ff"] scanHexInt:&codeValue];
NSLog(#"%C", (unichar)codeValue);
not leading by "\u" or "\\u", from API doc:
The hexadecimal integer representation may optionally be preceded
by 0x or 0X. Skips past excess digits in the case of overflow,
so the receiver’s position is past the entire hexadecimal representation.
I have a string representing a number, and I want to convert it an NSInteger. The problem is, that the string is formatted with thousand separators:
"1,234"
when using [value intValue], I get 1 as the value.
Is it because it thinks the thousand separator is a decimal separator? (my locale uses comma as decimal separator and a space or a dot as thousand separator)
How can I ensure that I get the right number?
-Vegar
There's the NSNumberFormatter class which can not only encode numbers, but also decode them according to the current locale.
I would find a class that can decode numbers from strings just as Georg suggests, but a quick solution could also be to chop off the extra thousand separators using the stringByReplacing… method of the NSString class.
NSString str = xxxxx;
[str length];
This code is number of characters.
I want to get number of byte.
Use -[NSString lengthOfBytesUsingEncoding:].
NSString is a unicode string. Thus, there is no such thing as byte length without specifying an encoding for the unicode code points of each letter in the string. As others have pointed out, once you choose an encoding,
-[NSString lengthOfBytesUsingEncoding:]
is what you need.
You might find this what-you-need-to-know tutorial on Unicode helpful.