Objective-c格式化输出格式

Objective-c格式化输出格式:

%@

Objective-C object, printed as the string returned by descriptionWithLocale: if available, or description otherwise. Also works with CFTypeRef objects, returning the result of the CFCopyDescription function.

%%

'%' character.

%d%D

Signed 32-bit integer (int).

%u%U

Unsigned 32-bit integer (unsigned int).

%x

Unsigned 32-bit integer (unsigned int), printed in hexadecimal using the digits 0–9 and lowercase a–f.

%X

Unsigned 32-bit integer (unsigned int), printed in hexadecimal using the digits 0–9 and uppercase A–F.

%o%O

Unsigned 32-bit integer (unsigned int), printed in octal.

%f

64-bit floating-point number (double).

%e

64-bit floating-point number (double), printed in scientific notation using a lowercase e to introduce the exponent.

%E

64-bit floating-point number (double), printed in scientific notation using an uppercase E to introduce the exponent.

%g

64-bit floating-point number (double), printed in the style of %e if the exponent is less than –4 or greater than or equal to the precision, in the style of %f otherwise.

%G

64-bit floating-point number (double), printed in the style of %E if the exponent is less than –4 or greater than or equal to the precision, in the style of %f otherwise.

%c

8-bit unsigned character (unsigned char), printed by NSLog() as an ASCII character, or, if not an ASCII character, in the octal format \\ddd or the Unicode hexadecimal format\\udddd, where d is a digit.

%C

16-bit Unicode character (unichar), printed by NSLog() as an ASCII character, or, if not an ASCII character, in the octal format \\ddd or the Unicode hexadecimal format \\udddd, where d is a digit.

%s

Null-terminated array of 8-bit unsigned characters. Because the %s specifier causes the characters to be interpreted in the system default encoding, the results can be variable, especially with right-to-left languages. For example, with RTL, %s inserts direction markers when the characters are not strongly directional. For this reason, it’s best to avoid %s and specify encodings explicitly.

%S

Null-terminated array of 16-bit Unicode characters.

%p

Void pointer (void *), printed in hexadecimal with the digits 0–9 and lowercase a–f, with a leading 0x.

%a

64-bit floating-point number (double), printed in scientific notation with a leading 0x and one hexadecimal digit before the decimal point using a lowercase p to introduce the exponent.

%A

64-bit floating-point number (double), printed in scientific notation with a leading 0X and one hexadecimal digit before the decimal point using a uppercase P to introduce the exponent.

%F

64-bit floating-point number (double), printed in decimal notation.

h

Length modifier specifying that a following doux, or X conversion specifier applies to ashort or unsigned short argument.

hh

Length modifier specifying that a following doux, or X conversion specifier applies to asigned char or unsigned char argument.

l

Length modifier specifying that a following doux, or X conversion specifier applies to along or unsigned long argument.

llq

Length modifiers specifying that a following doux, or X conversion specifier applies to along long or unsigned long long argument.

L

Length modifier specifying that a following aAeEfFg, or G conversion specifier applies to a long double argument.

z

Length modifier specifying that a following doux, or X conversion specifier applies to asize_t or the corresponding signed integer type argument.

t

Length modifier specifying that a following doux, or X conversion specifier applies to aptrdiff_t or the corresponding unsigned integer type argument.

j

Length modifier specifying that a following doux, or X conversion specifier applies to aintmax_t or uintmax_t argument.

NSInteger

%ld or %lx

Cast the value to long.

NSUInteger

%lu or %lx

Cast the value to unsigned long.

CGFloat

%f or %g

%f works for floats and doubles when formatting; but note the technique described below for scanning.

CFIndex

%ld or %lx

The same as NSInteger.

pointer

%p or %zx

%p adds 0x to the beginning of the output. If you don't want that, use%zx and no typecast.

摘自Programming Guide for Cocoa文档

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