uint64的格式化请用%llu , int64的格式化请用%lld
格式定义
The format specifiers supported by the NSString formatting methods and CFString formatting functions follow the IEEE printf specification; the specifiers are summarized in Table 1. Note that you can also use the “n$” positional specifiers such as %1$@ %2$s. For more details, see the IEEE printf specification. You can also use these format specifiers with the NSLog function.
Table 1 Format specifiers supported by the NSString formatting methods and CFString formatting functions
定义说明
%@ 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, %i Signed 32-bit integer (int)
%u, %U Unsigned 32-bit integer (unsigned int)
%hi Signed 16-bit integer (short)
%hu Unsigned 16-bit integer (unsigned short)
%qi Signed 64-bit integer (long long)
%qu Unsigned 64-bit integer (unsigned long long)
%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
%qx Unsigned 64-bit integer (unsigned long long), printed in hexadecimal using the digits 0–9 and lowercase a–f
%qX Unsigned 64-bit integer (unsigned long long), 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 orthe Unicode hexadecimal format \\udddd, where d is a digit
%s Null-terminated array of 8-bit unsigned characters. %s interprets its input in the system encoding rather than,
for example, UTF-8.
%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
%L Length modifier specifying that a following a, A, e, E, f, F, g, or G conversion specifier applies to a long double argument
%a 64-bit floating-point number (double), printed in scientific notation with a leading 0x and one hexadecimal digit
before the decimalpoint using a lowercase p to introduce the exponent
%A 64-bit floating-point number (double), printed in scientificnotation 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
%z Length modifier specifying that a following d, i, o, u, x, or X conversion specifier applies to a size_t or the corresponding
signed integer type argument
%t Length modifier specifying that a following d, i, o, u, x, or X conversion specifier applies to a ptrdiff_t or the
corresponding unsigned integer type argument
%j Length modifier specifying that a following d, i, o, u, x, or X conversion specifier applies to a intmax_t or
uintmax_t argument
平台依赖
Mac OS X uses several data types—NSInteger, NSUInteger,CGFloat, and CFIndex—to provide a consistent means of representing values in 32- and 64-bit environments. In a 32-bit environment, NSInteger and NSUInteger are defined as int and unsigned int, respectively. In 64-bit environments, NSInteger and NSUInteger are defined as long and unsigned long, respectively. To avoid the need to use different printf-style type specifiers depending on the platform, you can use the specifiers shown in Table 2. Note that in some cases you may have to cast the value.
Table 2 Format specifiers for data types
类型定义建议
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 see below warning when scanning
CFIndex %ld or %lx The same as NSInteger
pointer %p%p adds 0x to the beginning of the output. If you don’t want that, use %lx and cast to long.
long long %lld or %llx long long is 64-bit on both 32- and 64-bit platforms
unsigned long long %llu or %ll xunsigned long long is 64-bit on both 32- and 64-bit platforms
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