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目錄 搜尋
Algorithms Algorithms（算法） bsearch bsearch_s qsort qsort_s Atomic operations Atomic operations library（原子操作庫(kù)） ATOMIC_*_LOCK_FREE atomic_compare_exchange_strong atomic_compare_exchange_strong_explicit atomic_compare_exchange_weak atomic_compare_exchange_weak_explicit atomic_exchange atomic_exchange_explicit atomic_fetch_add atomic_fetch_add_explicit atomic_fetch_and atomic_fetch_and_explicit atomic_fetch_or atomic_fetch_or_explicit atomic_fetch_sub atomic_fetch_sub_explicit atomic_fetch_xor atomic_fetch_xor_explicit atomic_flag atomic_flag_clear atomic_flag_clear_explicit ATOMIC_FLAG_INIT atomic_flag_test_and_set atomic_flag_test_and_set_explicit atomic_init atomic_is_lock_free atomic_load atomic_load_explicit atomic_signal_fence atomic_store atomic_store_explicit atomic_thread_fence（線程圍欄） ATOMIC_VAR_INIT kill_dependency memory_order（內(nèi)存排序） C keywords auto（自動(dòng)存儲(chǔ)） break（跳出循環(huán)） C keywords（關(guān)鍵詞） case char const（常量修飾符） continue default（預(yù)設(shè)運(yùn)算式） do double（雙精度浮點(diǎn)型） else enum（枚舉類型） extern（全局變量） float（浮點(diǎn)數(shù)） for fortran goto（goto語(yǔ)句） if（if語(yǔ)句） inline（行內(nèi)函式） int long（長(zhǎng)整型） register（寄存器變量） restrict（ restrict類型限定符） return short signed sizeof（sizeof運(yùn)算符） static（靜態(tài)變量） struct（結(jié)構(gòu)體） switch（switch語(yǔ)句） typedef（typedef關(guān)鍵字） union（聯(lián)合體） unsigned（無(wú)符號(hào)） void（空類型） volatile（volatile變量） while（while語(yǔ)句） _Alignas _Alignof _Atomic _Bool _Complex _Generic _Imaginary _Noreturn _Static_assert _Thread_local C language #define directive #elif directive #else directive #endif directive #error directive #if directive #ifdef directive #ifndef directive #include directive #line directive #pragma directive alignas（對(duì)齊指定符） Alternative operators and tokens（替代運(yùn)算符和令牌） Analyzability Arithmetic operators Arithmetic types Array declaration（數(shù)組聲明） Array initialization（陣列初始化） ASCII Chart Assignment operators（賦值運(yùn)算符） types（atomic類型限定符） Basic concepts Bit fields（位域） break statement C language C Operator Precedence cast operator character constant（字符字面量） Comments（注釋符） Comparison operators（比較運(yùn)算符） compound literals（符合字面量） Conditional inclusion（條件包含） Conformance（一致性） const type qualifier（const 限定符） Constant expressions（常量表達(dá)） continue statement Declarations（聲明） do-while loop Enumerations（枚舉類型） Escape sequences（轉(zhuǎn)義字符） Expressions（表達(dá)式） External and tentative definitions（外部和暫定的定義） File scope（文件范圍） floating constant（浮點(diǎn)常量） for loop Function declarations（函數(shù)聲明） Function definitions（函數(shù)聲明） Functions Generic selection泛型選擇 goto statement Identifier（標(biāo)示符） if statement Implicit conversions（隱式轉(zhuǎn)換） Increment/decrement operators（前置/后置操作符） Initialization（初始化） inline function specifier（內(nèi)聯(lián)函式） integer constant Lifetime（生命期） Logical operators（邏輯運(yùn)算符） Lookup and name spaces Main function（主函式） Member access operators（會(huì)員接入運(yùn)營(yíng)商） Memory model Objects and alignment（字節(jié)對(duì)齊） Order of evaluation（評(píng)估順序） Other operators Phases of translation（翻譯階段） Pointer declaration Preprocessor（預(yù)處理） restrict type qualifier（restrict類型限定符） return statement Scalar initialization（標(biāo)量類型初始化） Scope（范圍） sizeof operator（sizeof運(yùn)算符） Statements（陳述） static assert declaration（靜態(tài)斷言聲明） Static storage duration（靜態(tài)存儲(chǔ)周期） Storage-class specifiers（存儲(chǔ)類說(shuō)明符） string literals（字符串字面量） Struct and union initialization（結(jié)構(gòu)體與聯(lián)合體初始化） Struct declaration（結(jié)構(gòu)體聲明） switch statement Thread storage duration（線程存儲(chǔ)時(shí)間） Type Type（類型） Typedef declaration（Typedef聲明） Undefined behavior（未定義行為） Union declaration（聯(lián)合體聲明） Value categories（值類別） Variadic arguments（變長(zhǎng)參數(shù)宏） volatile type qualifier（volatile 類型限定符） while loop _Alignof operator _Noreturn function specifier Date and time asctime（asctime函數(shù)） asctime_s clock CLOCKS_PER_SEC clock_t ctime（ctime函數(shù)） ctime_s Date and time utilities（日期和時(shí)間庫(kù)） difftime（計(jì)算兩個(gè)時(shí)間的間隔） gmtime gmtime_s localtime localtime_s mktime（將時(shí)間結(jié)構(gòu)數(shù)據(jù)轉(zhuǎn)換成經(jīng)過的秒數(shù)的函數(shù)） strftime（格式化輸出時(shí)間函數(shù)） time timespec timespec_get time_t tm wcsftime（格式化時(shí)間寬字符） Dynamic memory management aligned_alloc C memory management library（內(nèi)存管理庫(kù)） calloc free（釋放動(dòng)態(tài)分配空間的函數(shù)） malloc（動(dòng)態(tài)分配內(nèi)存空間的函數(shù)） realloc（重新分配內(nèi)存空間的函數(shù)） Error handling abort_handler_s assert（斷言） constraint_handler_t errno（錯(cuò)誤報(bào)告） Error handling（錯(cuò)誤處理） Error numbers（錯(cuò)誤個(gè)數(shù)） ignore_handler_s set_constraint_handler_s static_assert File input/output clearerr（清除/復(fù)位） fclose feof ferror fflush（清空文件緩沖區(qū)） fgetc fgetpos fgets fgetwc fgetws File input/output fopen fopen_s fprintf fprintf_s fputc fputs fputwc fputws fread freopen freopen_s fscanf fscanf_s fseek fsetpos ftell fwide fwprintf fwprintf_s fwrite fwscanf fwscanf_s getc getchar gets gets_s getwchar perror printf printf_s putc putchar puts putwc putwchar remove rename rewind scanf scanf_s setbuf setvbuf snprintf sprintf sscanf sscanf_s swprintf swprintf_s swscanf swscanf_s tmpfile tmpfile_s tmpnam tmpnam_s ungetc ungetwc vfprintf vfprintf_s vfscanf vfscanf_s vfwprintf vfwprintf_s vfwscanf vfwscanf_s vprintf vprintf_s vscanf vscanf_s vsnprintf vsprintf vsscanf vsscanf_s vswprintf vswprintf_s vswscanf vswscanf_s vwprintf vwprintf_s vwscanf vwscanf_s wprintf wprintf_s wscanf wscanf_s Localization support lconv LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME localeconv Localization support setlocale Numerics abs acos acosf acosh acoshf acoshl acosl asin asinf asinh asinhf asinhl asinl atan atan2 atan2f atan2l atanf atanh atanhf atanhl atanl cabs cabsf cabsl cacos cacosf cacosh cacoshf cacoshl cacosl carg cargf cargl casin casinf casinh casinhf casinhl casinl catan catanf catanh catanhf catanhl catanl cbrt cbrtf cbrtl ccos ccosf ccosh ccoshf ccoshl ccosl ceil ceilf ceill cexp cexpf cexpl cimag cimagf cimagl clog clogf clogl CMPLX CMPLXF CMPLXL Common mathematical functions complex Complex number arithmetic conj conjf conjl copysign copysignf copysignl cos cosf cosh coshf coshl cosl cpow cpowf cpowl cproj cprojf cprojl creal crealf creall csin csinf csinh csinhf csinhl csinl csqrt csqrtf csqrtl ctan ctanf ctanh ctanhf ctanhl ctanl div double_t erf erfc erfcf erfcl erff erfl exp exp2 exp2f exp2l expf expl expm1 expm1f expm1l fabs fabsf fabsl fdim feclearexcept fegetenv fegetexceptflag fegetround feholdexcept feraiseexcept fesetenv fesetexceptflag fesetround fetestexcept feupdateenv FE_ALL_EXCEPT FE_DFL_ENV FE_DIVBYZERO FE_DOWNWARD FE_INEXACT FE_INVALID FE_OVERFLOW FE_TONEAREST FE_TOWARDZERO FE_UNDERFLOW FE_UPWARD Floating-point environment float_t floor floorf floorl fma fmaf fmal fmax fmaxf fmaxl fmin fminf fminl fmod fmodf fmodl fpclassify FP_INFINITE FP_NAN FP_NORMAL FP_SUBNORMAL FP_ZERO frexp frexpf frexpl HUGE_VAL HUGE_VALF HUGE_VALL hypot hypotf hypotl I ilogb ilogbf ilogbl imaginary imaxabs imaxdiv INFINITY isfinite isgreater isgreaterequal isinf isless islessequal islessgreater isnan isnormal isunordered labs ldexp ldexpf ldexpl ldiv lgamma lgammaf lgammal llabs lldiv llrint llrintf llrintl llround llroundf llroundl log log10 log10f log10l log1p log1pf log1pl log2 log2f log2l logb logbf logbl logf logl lrint lrintf lrintl lround lroundf lroundl MATH_ERREXCEPT math_errhandling MATH_ERRNO modf modff modfl nan NAN nanf nanl nearbyint nearbyintf nearbyintl nextafter nextafterf nextafterl nexttoward nexttowardf nexttowardl Numerics pow powf powl Pseudo-random number generation rand RAND_MAX remainder remainderf remainderl remquo remquof remquol rint rintf rintl round roundf roundl scalbln scalblnf scalblnl scalbn scalbnf scalbnl signbit sin sinf sinh sinhf sinhl sinl sqrt sqrtf sqrtl srand tan tanf tanh tanhf tanhl tanl tgamma tgammaf tgammal trunc truncf truncl Type-generic math _Complex_I _Imaginary_I Program support abort atexit at_quick_exit exit EXIT_FAILURE EXIT_SUCCESS getenv getenv_s jmp_buf longjmp Program support utilities quick_exit raise setjmp SIGABRT SIGFPE SIGILL SIGINT signal SIGSEGV SIGTERM sig_atomic_t SIG_DFL SIG_ERR SIG_IGN system _Exit Strings atof atoi atol atoll btowc c16rtomb c32rtomb char16_t char32_t isalnum isalpha isblank iscntrl isdigit isgraph islower isprint ispunct isspace isupper iswalnum iswalpha iswblank iswcntrl iswctype iswdigit iswgraph iswlower iswprint iswpunct iswspace iswupper iswxdigit isxdigit mblen mbrlen mbrtoc16 mbrtoc32 mbrtowc mbsinit mbsrtowcs mbsrtowcs_s mbstate_t mbstowcs mbstowcs_s mbtowc memchr memcmp memcpy memcpy_s memmove memmove_s memset memset_s Null-terminated byte strings Null-terminated multibyte strings Null-terminated wide strings strcat strcat_s strchr strcmp strcoll strcpy strcpy_s strcspn strerror strerrorlen_s strerror_s Strings library strlen strncat Thread support call_once cnd_broadcast cnd_destroy cnd_init cnd_signal cnd_timedwait cnd_wait mtx_destroy mtx_init mtx_lock mtx_plain mtx_recursive mtx_timed mtx_timedlock mtx_trylock mtx_unlock once_flag ONCE_FLAG_INIT thrd_busy thrd_create thrd_current thrd_detach thrd_equal thrd_error thrd_exit thrd_join thrd_nomem thrd_sleep thrd_success thrd_timedout thrd_yield Thread support library thread_local tss_create tss_delete TSS_DTOR_ITERATIONS tss_get tss_set Type support Boolean type support library Fixed width integer types FLT_EVAL_METHOD FLT_ROUNDS max_align_t NULL Numeric limits offsetof ptrdiff_t size_t Type support Variadic functions Variadic functions va_arg va_copy va_end va_list va_start
文字

在頭文件<stdio.h>中定義




(1)


int scanf（const char * format，...）;

（直到C99）


int scanf（const char * restrict format，...）;

（自C99以來(lái)）



(2)


int fscanf（FILE * stream，const char * format，...）;

（直到C99）


int fscanf（FILE * restrict stream，const char * restrict format，...）;

（自C99以來(lái)）



(3)


int sscanf（const char * buffer，const char * format，...）;

（直到C99）


int sscanf（const char *限制緩沖區(qū)，const char *限制格式，...）;

（自C99以來(lái)）


int scanf_s（const char * restrict format，...）;

(4)

（自C11以來(lái)）

int fscanf_s（FILE * restrict stream，const char * restrict format，...）;

(5)

（自C11以來(lái)）

int sscanf_s（const char *限制緩沖區(qū)，const char *限制格式，...）;

(6)

（自C11以來(lái)）

從各種來(lái)源讀取數(shù)據(jù)，根據(jù)其解釋并將format結(jié)果存儲(chǔ)到給定位置。

1）從中讀取數(shù)據(jù) stdin

2）從文件流中讀取數(shù)據(jù) stream

3）從空終止的字符串中讀取數(shù)據(jù)buffer。到達(dá)字符串的末尾等同于達(dá)到文件結(jié)束條件fscanf

4-6）與（1-3）相同，不同之處在于%c，%s和%[轉(zhuǎn)換說(shuō)明符每個(gè)都需要兩個(gè)參數(shù)（通常的指針和rsize_t表示接收數(shù)組大小的類型值，當(dāng)使用％c讀取時(shí)可能為1成一個(gè)字符），除了在運(yùn)行時(shí)檢測(cè)到以下錯(cuò)誤并調(diào)用當(dāng)前安裝的約束處理函數(shù)：

  • 指針類型的任何參數(shù)都是空指針

  • format，stream或者buffer是空指針

  • ％c，％s或％[，加上終止空字符，將會(huì)超過為每個(gè)轉(zhuǎn)換說(shuō)明符提供的第二個(gè)（rsize_t）參數(shù)所寫的字符數(shù)

  • 可選地，還有任何其他可檢測(cè)到的錯(cuò)誤，例如未知的轉(zhuǎn)換說(shuō)明符

由于所有的邊界檢查功能，scanf_s，fscanf_s，和sscanf_s僅保證可供如果__STDC_LIB_EXT1__由實(shí)現(xiàn)所定義，并且如果用戶定義__STDC_WANT_LIB_EXT1__的整數(shù)常數(shù)1，包括之前<stdio.h>。

參數(shù)

流

-

輸入文件流從中讀取



















































































緩沖

-

指向以null結(jié)尾的字符串讀取的指針



















































































格式

-

pointer to a null-terminated character string specifying how to read the input. The format string consists of.   non-whitespace multibyte characters except %: each such character in the format string consumes exactly one identical character from the input stream, or causes the function to fail if the next character on the stream does not compare equal.   whitespace characters: any single whitespace character in the format string consumes all available consecutive whitespace characters from the input (determined as if by calling isspace in a loop). Note that there is no difference between "\n", " ", "\t\t", or other whitespace in the format string.   conversion specifications. Each conversion specification has the following format:    introductory % character   (optional) assignment-suppressing character *. If this option is present, the function does not assign the result of the conversion to any receiving argument.   (optional) integer number (greater than zero) that specifies maximum field width, that is, the maximum number of characters that the function is allowed to consume when doing the conversion specified by the current conversion specification. Note that %s and %[ may lead to buffer overflow if the width is not provided.   (optional) length modifier that specifies the size of the receiving argument, that is, the actual destination type. This affects the conversion accuracy and overflow rules. The default destination type is different for each conversion type (see table below).   conversion format specifier         The following format specifiers are available:    Conversion specifier   Explanation   Argument type     length modifier   hh (C99).   h   (none)   l   ll (C99).   j (C99).   z (C99).   t (C99).   L     %   matches literal %   N/A   N/A   N/A   N/A   N/A   N/A   N/A   N/A   N/A     c    matches a character or a sequence of characters  If a width specifier is used, matches exactly width characters (the argument must be a pointer to an array with sufficient room). Unlike %s and %[, does not append the null character to the array.   N/A   N/A   char*   wchar_t*   N/A   N/A   N/A   N/A   N/A     s    matches a sequence of non-whitespace characters (a string)  If width specifier is used, matches up to width or until the first whitespace character, whichever appears first. Always stores a null character in addition to the characters matched (so the argument array must have room for at least width+1 characters).     set   matches a non-empty sequence of character from set of characters.  If the first character of the set is ^, then all characters not in the set are matched. If the set begins with ] or ^] then the ] character is also included into the set. It is implementation-defined whether the character - in the non-initial position in the scanset may be indicating a range, as in 0-9. If width specifier is used, matches only up to width. Always stores a null character in addition to the characters matched (so the argument array must have room for at least width+1 characters).     d   matches a decimal integer.  The format of the number is the same as expected by strtol() with the value 10 for the base argument.    signed char* or unsigned char*     signed short* or unsigned short*     signed int* or unsigned int*     signed long* or unsigned long*     signed long long* or unsigned long long*     intmax_t* or uintmax_t*    size_t*   ptrdiff_t*   N/A     i   matches an integer.  The format of the number is the same as expected by strtol() with the value 0 for the base argument (base is determined by the first characters parsed).     u   matches an unsigned decimal integer.  The format of the number is the same as expected by strtoul() with the value 10 for the base argument.     o   matches an unsigned octal integer.  The format of the number is the same as expected by strtoul() with the value 8 for the base argument.     x, X   matches an unsigned hexadecimal integer.  The format of the number is the same as expected by strtoul() with the value 16 for the base argument.     n   returns the number of characters read so far.  No input is consumed. Does not increment the assignment count. If the specifier has assignment-suppressing operator defined, the behavior is undefined.     a, A(C99) e, E f, F g, G   matches a floating-point number.  The format of the number is the same as expected by strtof().   N/A   N/A   float*   double*   N/A   N/A   N/A   N/A   long double*     p   matches implementation defined character sequence defining a pointer.  printf family of functions should produce the same sequence using %p format specifier.   N/A   N/A   void**   N/A   N/A   N/A   N/A   N/A   N/A    For every conversion specifier other than n, the longest sequence of input characters which does not exceed any speci?ed ?eld width and which either is exactly what the conversion specifier expects or is a prefix of a sequence it would expect, is what's consumed from the stream. The ?rst character, if any, after this consumed sequence remains unread. If the consumed sequence has length zero or if the consumed sequence cannot be converted as specified above, the matching failure occurs unless end-of-?le, an encoding error, or a read error prevented input from the stream, in which case it is an input failure. All conversion specifiers other than [, c, and n consume and discard all leading whitespace characters (determined as if by calling isspace) before attempting to parse the input. These consumed characters do not count towards the specified maximum field width. The conversion specifiers lc, ls, and l[ perform multibyte-to-wide character conversion as if by calling mbrtowc() with an mbstate_t object initialized to zero before the first character is converted. The conversion specifiers s and [ always store the null terminator in addition to the matched characters. The size of the destination array must be at least one greater than the specified field width. The use of %s or %[, without specifying the destination array size, is as unsafe as gets. The correct conversion specifications for the fixed-width integer types (int8_t, etc) are defined in the header <inttypes.h> (although SCNdMAX, SCNuMAX, etc is synonymous with %jd, %ju, etc). There is a sequence point after the action of each conversion specifier; this permits storing multiple fields in the same "sink" variable. When parsing an incomplete floating-point value that ends in the exponent with no digits, such as parsing "100er" with the conversion specifier %f, the sequence "100e" (the longest prefix of a possibly valid floating-point number) is consumed, resulting in a matching error (the consumed sequence cannot be converted to a floating-point number), with "r" remaining. Existing implementations do not follow this rule and roll back to consume only "100", leaving "er", e.g. glibc bug 1765.

Conversion specifier

Explanation

Argument type

length modifier

hh (C99).

h

(none)

l

ll (C99).

j (C99).

z (C99).

t (C99).

L

%

matches literal %

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

c

matches a character or a sequence of characters  If a width specifier is used, matches exactly width characters (the argument must be a pointer to an array with sufficient room). Unlike %s and %[, does not append the null character to the array.

N/A

N/A

char*

wchar_t*

N/A

N/A

N/A

N/A

N/A

s

matches a sequence of non-whitespace characters (a string)  If width specifier is used, matches up to width or until the first whitespace character, whichever appears first. Always stores a null character in addition to the characters matched (so the argument array must have room for at least width+1 characters).

set

matches a non-empty sequence of character from set of characters.  If the first character of the set is ^, then all characters not in the set are matched. If the set begins with ] or ^] then the ] character is also included into the set. It is implementation-defined whether the character - in the non-initial position in the scanset may be indicating a range, as in 0-9. If width specifier is used, matches only up to width. Always stores a null character in addition to the characters matched (so the argument array must have room for at least width+1 characters).

d

matches a decimal integer.  The format of the number is the same as expected by strtol() with the value 10 for the base argument.

signed char* or unsigned char*

signed short* or unsigned short*

signed int* or unsigned int*

signed long* or unsigned long*

signed long long* or unsigned long long*

intmax_t* or uintmax_t*

size_t*

ptrdiff_t*

N/A

i

matches an integer.  The format of the number is the same as expected by strtol() with the value 0 for the base argument (base is determined by the first characters parsed).

u

matches an unsigned decimal integer.  The format of the number is the same as expected by strtoul() with the value 10 for the base argument.

o

matches an unsigned octal integer.  The format of the number is the same as expected by strtoul() with the value 8 for the base argument.

x, X

matches an unsigned hexadecimal integer.  The format of the number is the same as expected by strtoul() with the value 16 for the base argument.

n

returns the number of characters read so far.  No input is consumed. Does not increment the assignment count. If the specifier has assignment-suppressing operator defined, the behavior is undefined.

a, A(C99) e, E f, F g, G

matches a floating-point number.  The format of the number is the same as expected by strtof().

N/A

N/A

float*

double*

N/A

N/A

N/A

N/A

long double*

p

matches implementation defined character sequence defining a pointer.  printf family of functions should produce the same sequence using %p format specifier.

N/A

N/A

void**

N/A

N/A

N/A

N/A

N/A

N/A

Conversion specifier

Explanation

Argument type



















































































length modifier

hh (C99).

h

(none)

l

ll (C99).

j (C99).

z (C99).

t (C99).

L












































































%

matches literal %

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A











































































c

matches a character or a sequence of characters  If a width specifier is used, matches exactly width characters (the argument must be a pointer to an array with sufficient room). Unlike %s and %[, does not append the null character to the array.

N/A

N/A

char*

wchar_t*

N/A

N/A

N/A

N/A

N/A











































































s

matches a sequence of non-whitespace characters (a string)  If width specifier is used, matches up to width or until the first whitespace character, whichever appears first. Always stores a null character in addition to the characters matched (so the argument array must have room for at least width+1 characters).




















































































set

matches a non-empty sequence of character from set of characters.  If the first character of the set is ^, then all characters not in the set are matched. If the set begins with ] or ^] then the ] character is also included into the set. It is implementation-defined whether the character - in the non-initial position in the scanset may be indicating a range, as in 0-9. If width specifier is used, matches only up to width. Always stores a null character in addition to the characters matched (so the argument array must have room for at least width+1 characters).




















































































d

matches a decimal integer.  The format of the number is the same as expected by strtol() with the value 10 for the base argument.

signed char* or unsigned char*

signed short* or unsigned short*

signed int* or unsigned int*

signed long* or unsigned long*

signed long long* or unsigned long long*

intmax_t* or uintmax_t*

size_t*

ptrdiff_t*

N/A











































































i

matches an integer.  The format of the number is the same as expected by strtol() with the value 0 for the base argument (base is determined by the first characters parsed).




















































































u

matches an unsigned decimal integer.  The format of the number is the same as expected by strtoul() with the value 10 for the base argument.




















































































o

matches an unsigned octal integer.  The format of the number is the same as expected by strtoul() with the value 8 for the base argument.




















































































x, X

matches an unsigned hexadecimal integer.  The format of the number is the same as expected by strtoul() with the value 16 for the base argument.




















































































n

returns the number of characters read so far.  No input is consumed. Does not increment the assignment count. If the specifier has assignment-suppressing operator defined, the behavior is undefined.




















































































a，A（C99）e，E f，F(xiàn) g，G

匹配一個(gè)浮點(diǎn)數(shù)。數(shù)字的格式與strtof（）的預(yù)期相同。

N / A

N / A

浮動(dòng)*

雙*

N / A

N / A

N / A

N / A

長(zhǎng)雙*











































































p

匹配定義指針的實(shí)現(xiàn)定義的字符序列。printf系列函數(shù)應(yīng)該使用％p格式說(shuō)明符產(chǎn)生相同的序列。

N / A

N / A

無(wú)效**

N / A

N / A

N / A

N / A

N / A

N / A











































































...

-

接收參數(shù)



















































































  • 非空白多字節(jié)字符除外%：格式字符串中的每個(gè)這樣的字符只消耗輸入流中的一個(gè)完全相同的字符，或者如果流中的下一個(gè)字符不相等，則會(huì)導(dǎo)致函數(shù)失敗。

  • 空白字符：格式字符串中的任何單個(gè)空白字符都會(huì)消耗輸入中所有可用的連續(xù)空白字符（如同通過調(diào)用isspace循環(huán)來(lái)確定）。請(qǐng)注意，有沒有什么區(qū)別"\n"，" "，"\t\t"在格式字符串或其他空白。

  • 轉(zhuǎn)換規(guī)格。每個(gè)轉(zhuǎn)換規(guī)范具有以下格式：

    • 介紹%人物

    • （可選）分配抑制字符*。如果存在此選項(xiàng)，則函數(shù)不會(huì)將轉(zhuǎn)換結(jié)果分配給任何接收參數(shù)。

    • （可選）指定最大字段寬度的整數(shù)數(shù)字（大于零），即該函數(shù)在執(zhí)行由當(dāng)前轉(zhuǎn)換規(guī)范指定的轉(zhuǎn)換時(shí)允許使用的最大字符數(shù)。請(qǐng)注意，如果未提供寬度，％s和％[可能會(huì)導(dǎo)致緩沖區(qū)溢出。

    • （可選）長(zhǎng)度修飾符，用于指定接收參數(shù)的大小，即實(shí)際的目標(biāo)類型。這會(huì)影響轉(zhuǎn)換精度和溢出規(guī)則。每種轉(zhuǎn)換類型的默認(rèn)目標(biāo)類型都不相同（請(qǐng)參閱下表）。

    • 轉(zhuǎn)換格式說(shuō)明符

以下格式說(shuō)明符可用：

Conversion

說(shuō)明符說(shuō)明參數(shù)類型長(zhǎng)度修飾符    hh（C99）。

h   (none)   l   ll (C99).

j (C99).

z (C99).

t (C99).

L %   匹配字面%   N / AN / AN / AN / AN / AN / AN / AN / AN / A      c    一個(gè)匹配字符或序列字符如果使用寬度說(shuō)明，完全匹配寬度的字符（參數(shù)必須是一個(gè)指針數(shù)組有足夠的空間）。與％s和％[不同，不會(huì)將空字符追加到數(shù)組。

N/A   N/A   char*

wchar_t*

N / AN / AN / AN / AN / A      s    匹配非空白字符序列（字符串）如果使用寬度說(shuō)明符，則匹配寬度或直到第一個(gè)空白字符，以先出現(xiàn)者為準(zhǔn)。除了匹配的字符外，總是存儲(chǔ)一個(gè)空字符（所以參數(shù)數(shù)組必須至少有寬度+ 1個(gè)字符的空間）。

 `[`set`]`   matches a non-empty sequence of character from set of characters.  If the first character of the set is `^`, then all characters not in the set are matched. If the set begins with `]` or `^]` then the `]` character is also included into the set. It is implementation-defined whether the character `-` in the non-initial position in the scanset may be indicating a range, as in `[0-9]`. If width specifier is used, matches only up to _width_. Always stores a null character in addition to the characters matched (so the argument array must have room for at least _width+1_ characters).
 `d`   matches a **decimal integer**.  The format of the number is the same as expected by [`strtol()`](../string/byte/strtol) with the value `10` for the `base` argument.
`signed char*` or `unsigned char*`
`signed short*` or `unsigned short*`
`signed int*` or `unsigned int*`
`signed long*` or `unsigned long*`
`signed long long*` or `unsigned long long*`
[`intmax_t`](../types/integer)`*` or [`uintmax_t`](../types/integer)`*`

size_t*

ptrdiff_t*

N / A      i   匹配整數(shù)。數(shù)的格式是相同的通過按預(yù)期strtol()與值0的base參數(shù)（基部由解析的第一字符確定）。

 `u`   matches an unsigned **decimal integer**.  The format of the number is the same as expected by [`strtoul()`](../string/byte/strtoul) with the value `10` for the `base` argument.
 `o`   matches an unsigned **octal integer**.  The format of the number is the same as expected by [`strtoul()`](../string/byte/strtoul) with the value `8` for the `base` argument.
 `x`, `X`   matches an unsigned **hexadecimal integer**.  The format of the number is the same as expected by [`strtoul()`](../string/byte/strtoul) with the value `16` for the `base` argument.
 `n`   returns the **number of characters read so far**.  No input is consumed. Does not increment the assignment count. If the specifier has assignment-suppressing operator defined, the behavior is undefined.
 `a`, `A`(C99)

e, E

f, F

g，G   匹配一個(gè)浮點(diǎn)數(shù)。數(shù)字的格式與預(yù)期的相同strtof()。

N/A   N/A   float*

double*

N/A   N/A   N/A   N/A   long double*

 `p`   matches implementation defined character sequence defining a **pointer**.  `printf` family of functions should produce the same sequence using `%p` format specifier.

N/A   N/A   void**

n不適用不適用不適用不適用不適用不適用不適用不適用于任何指定字段寬度的最長(zhǎng)輸入字符序列的   每個(gè)轉(zhuǎn)換說(shuō)明符，或者正是轉(zhuǎn)換說(shuō)明符所期望的或者是它期望的順序是從流中消耗的。在消耗序列之后的第一個(gè)字符（如果有的話）仍然未讀。如果消耗的序列長(zhǎng)度為零或消費(fèi)的序列不能如上所述進(jìn)行轉(zhuǎn)換，則會(huì)發(fā)生匹配失敗，除非文件結(jié)束，編碼錯(cuò)誤或讀取錯(cuò)誤阻止了來(lái)自流的輸入，在這種情況下，它是輸入失敗。

在嘗試解析輸入之前，除了[，，之外的所有轉(zhuǎn)換說(shuō)明符都會(huì)消耗并放棄所有前導(dǎo)空白字符（如同通過調(diào)用一樣確定）。這些消耗的字符不會(huì)計(jì)入指定的最大字段寬度。cnisspace

轉(zhuǎn)換說(shuō)明符lc，ls并l[執(zhí)行多字節(jié)到寬字符轉(zhuǎn)換，就好像通過在第一個(gè)字符轉(zhuǎn)換之前使用初始化為零mbrtowc()的mbstate_t對(duì)象調(diào)用一樣。

除了匹配的字符之外，轉(zhuǎn)換說(shuō)明符s并[始終存儲(chǔ)空終止符。目標(biāo)數(shù)組的大小必須至少比指定的字段寬度大1。在不指定目標(biāo)數(shù)組大小的情況下，使用%s或%[不安全gets。

對(duì)于固定寬度的整數(shù)類型（正確的轉(zhuǎn)換規(guī)格int8_t<inttypes.h>還（雖然，等等）都在頭定義SCNdMAX，SCNuMAX等是同義詞%jd，%ju等）。

每個(gè)轉(zhuǎn)換說(shuō)明符的操作之后都有一個(gè)序列點(diǎn); 這允許將多個(gè)字段存儲(chǔ)在相同的“匯”變量中。

在解析指數(shù)中不包含數(shù)字的不完整浮點(diǎn)值時(shí)（例如"100er"使用轉(zhuǎn)換說(shuō)明符進(jìn)行解析），會(huì)消耗%f序列"100e"（可能有效的浮點(diǎn)數(shù)的最長(zhǎng)前綴），從而導(dǎo)致匹配錯(cuò)誤（消耗的序列不能轉(zhuǎn)換為浮點(diǎn)數(shù)），"r"剩余的?，F(xiàn)有的實(shí)現(xiàn)不遵循此規(guī)則并僅回滾消耗"100"，只留下"er"例如glibc錯(cuò)誤1765。

 ...   -   receiving arguments

返回值

1-3）成功分配的接收參數(shù)數(shù)量（EOF如果在分配第一個(gè)接收參數(shù)之前發(fā)生匹配故障，則可能為零），或者在分配第一個(gè)接收參數(shù)前發(fā)生輸入故障。

4-6）與（1-3）相同，但是EOF如果存在運(yùn)行時(shí)約束沖突，也會(huì)返回。

注意

由于大多數(shù)轉(zhuǎn)換說(shuō)明符首先消耗所有連續(xù)的空白，所以代碼如。

scanf("%d", &a);scanf("%d", &b);

將讀取在不同行上輸入的兩個(gè)整數(shù)（第二個(gè)％d將使用第一個(gè)剩下的換行符）或在同一行上，由空格或制表符分隔（第二個(gè)％d將使用空格或制表符）。不使用前導(dǎo)空格的轉(zhuǎn)換說(shuō)明符（如％c）可以通過在格式字符串中使用空格字符來(lái)完成：

scanf("%d", &a);scanf(" %c", &c); // ignore the endline after %d, then read a char

例

#define __STDC_WANT_LIB_EXT1__ 1#include <stdio.h>#include <stddef.h>#include <locale.h>
 int main(void){
    int i, j;
    float x, y;
    char str1[10], str2[4];
    wchar_t warr[2];    setlocale(LC_ALL, "en_US.utf8");
 
    char input[] = "25 54.32E-1 Thompson 56789 0123 56?水";    /* parse as follows:
       %d: an integer
       %f: a floating-point value
       %9s: a string of at most 9 non-whitespace characters
       %2d: two-digit integer (digits 5 and 6)
       %f:  a floating-point value (digits 7, 8, 9)
       %*d: an integer which isn't stored anywhere
       ' ': all consecutive whitespace
       %3[0-9]: a string of at most 3 decimal digits (digits 5 and 6)
       %2lc: two wide characters, using multibyte to wide conversion  */
    int ret = sscanf(input, "%d%f%9s%2d%f%*d %3[0-9]%2lc",                     &i, &x, str1, &j, &y, str2, warr); 
    printf("Converted %d fields:\ni = %d\nx = %f\nstr1 = %s\n"           "j = %d\ny = %f\nstr2 = %s\n"           "warr[0] = U+%x warr[1] = U+%x\n",
           ret, i, x, str1, j, y, str2, warr[0], warr[1]);
 #ifdef __STDC_LIB_EXT1__
    int n = sscanf_s(input, "%d%f%s", &i, &x, str1, (rsize_t)sizeof str1);    // writes 25 to i, 5.432 to x, the 9 bytes "thompson\0" to str1, and 3 to n.#endif}

輸出：

Converted 7 fields:i = 25x = 5.432000str1 = Thompson
j = 56y = 789.000000str2 = 56warr[0] = U+df warr[1] = U+6c34

參考

  • C11標(biāo)準(zhǔn)（ISO / IEC 9899：2011）：

    • 7.21.6.2 fscanf函數(shù)（p：317-324）

    • 7.21.6.4 scanf函數(shù)（p：325）

    • 7.21.6.7 sscanf函數(shù)（p：326）

    • K.3.5.3.2 fscanf_s函數(shù)（p：592-593）

    • K.3.5.3.4 scanf_s函數(shù)（p：594）

    • K.3.5.3.7 sscanf_s函數(shù)（p：596）

  • C99標(biāo)準(zhǔn)（ISO / IEC 9899：1999）：

    • 7.19.6.2 fscanf函數(shù)（p：282-289）

    • 7.19.6.4 scanf函數(shù)（p：290）

    • 7.19.6.7 sscanf函數(shù)（p：291）

  • C89 / C90標(biāo)準(zhǔn)（ISO / IEC 9899：1990）：

    • 4.9.6.2 fscanf函數(shù)

    • 4.9.6.4 scanf函數(shù)

    • 4.9.6.6 sscanf函數(shù)

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