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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
テキスト

在头文件<string.h>中定义




(1)


char * strcpy(char * dest,const char * src);

(直到C99)


char * strcpy(char * restrict dest,const char * restrict src);

(自C99以来)


errno_t strcpy_s(char * restrict dest,rsize_t destsz,const char * restrict src);

(2)

(自C11以来)

1)将由src指向的空终止字节字符串(包括空终止符)复制到第一个元素由dest指向的字符数组中。

如果dest数组不够大,行为是不确定的。 如果字符串重叠,则行为未定义。 如果dest不是指向字符数组的指针,或者src不是指向以空字符结尾的字节字符串的指针,则行为是未定义的。

2)与(1)相同,除了可以用未指定的值来摧毁目标数组的其余部分,并且在运行时检测到以下错误并调用当前安装的约束处理函数:

  • src或者dest是空指针

  • destsz 是零或大于 RSIZE_MAX

  • destsz小于或等于strnlen_s(src, destsz); 换句话说,会发生截断

  • 源和目标字符串之间会发生重叠

如果由dest <= strnlen_s(src,destsz)<destsz;指向的字符数组的大小,行为是未定义的。 换句话说,destsz的错误值不会暴露即将发生的缓冲区溢出。 作为所有边界检查函数,只有当__STDC_LIB_EXT1__由实现定义并且在包含string.h之前用户将__STDC_WANT_LIB_EXT1__定义为整数常量1时,strcpy_s才能保证可用。

参数

dest

-

指向要写入的字符数组的指针

src

-

指向要从中复制的以null结尾的字节字符串

destsz

-

最大写入字符数,通常是目标缓冲区的大小

返回值

1)返回dest 副本

2)在成功时返回零,错误时返回非零值。 此外,如果出错,则将零写入dest [0](除非dest为空指针或destsz为零或大于RSIZE_MAX)。

注意

允许strcpy_s从最后一个写入destsz的字符中截断目标数组,以提高效率:它可以复制多字节块,然后检查空字节。

函数strcpy_s与BSD函数strlcpy相似,除以下情况:

  • strlcpy 截断源字符串以适应目标(这是一种安全风险)

  • strlcpy不执行所有的运行时检查是strcpy_s不会

  • strlcpy 通过将目标设置为空字符串或在调用失败时调用处理程序不会使失败变得明显。

尽管strcpy_s由于潜在的安全风险而禁止截断,但可以使用bounds-checked strncpy_s来截断字符串。

#define __STDC_WANT_LIB_EXT1__ 1#include <string.h>#include <stdio.h>#include <stdlib.h>
 int main(void){
    char *src = "Take the test.";//  src[0] = 'M' ; // this would be undefined behavior
    char dst[strlen(src) + 1]; // +1 to accomodate for the null terminator    strcpy(dst, src);
    dst[0] = 'M'; // OK    printf("src = %s\ndst = %s\n", src, dst);
 #ifdef __STDC_LIB_EXT1__    set_constraint_handler_s(ignore_handler_s);
    int r = strcpy_s(dst, sizeof dst, src);    printf("dst = \"%s\", r = %d\n", dst, r);
    r = strcpy_s(dst, sizeof dst, "Take even more tests.");    printf("dst = \"%s\", r = %d\n", dst, r);#endif}

可能的输出:

src = Take the test.dst = Make the test.dst = "Take the test.", r = 0dst = "", r = 22

参考

  • C11标准(ISO / IEC 9899:2011):

    • 7.24.2.3 strcpy函数(p:363)

    • K.3.7.1.3 strcpy_s函数(p:615-616)

  • C99标准(ISO / IEC 9899:1999):

    • 7.21.2.3 strcpy函数(p:326)

  • C89 / C90标准(ISO / IEC 9899:1990):

    • 4.11.2.3 strcpy函数

扩展内容

strncpystrncpy_s(C11)

将一定数量的字符从一个字符串复制到另一个字符串(函数)

memcpymemcpy_s(C11)

将一个缓冲区复制到另一个(功能)

wcscpywcscpy_s(C95)(C11)

将一个宽字符串复制到另一个(函数)

strdup(动态内存TR)

分配一个字符串(函数)的副本

| 用于strcpy的C ++文档 |

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在头文件<wctype.h>中定义



int iswdigit(wint_t ch);


(自C95以来)

检查给定的宽字符是否对应(如果缩小)十个十进制数字字符0123456789中的一个。

参数

CH

-

宽字符

返回值

如果宽字符是数字字符,则为非零值,否则为零。

注意

iswdigitiswxdigit是唯一不受当前安装的C语言环境影响的标准宽字符分类函数。

一些语言环境提供了检测非ASCII数字的附加字符类。

#include <stdio.h>#include <wctype.h>#include <wchar.h>#include <locale.h> void test(wchar_t a3, wchar_t u3, wchar_t j3){    printf("        '%lc' '%lc' '%lc'\n", a3, u3, j3);    printf("iswdigit %d    %d   %d\n",           !!iswdigit(a3), !!iswdigit(u3), !!iswdigit(j3));    printf("jdigit:  %d    %d   %d\n", !!iswctype(a3, wctype("jdigit")),          !!iswctype(u3, wctype("jdigit")),          !!iswctype(j3, wctype("jdigit")));}
 int main(void){
    wchar_t a3 = L'3';  // the ASCII digit 3
    wchar_t u3 = L'三'; // the CJK numeral 3
    wchar_t j3 = L'3'; // the fullwidth digit 3 
    setlocale(LC_ALL, "en_US.utf8");    puts("In American locale:");    test(a3, u3, j3); 
    setlocale(LC_ALL, "ja_JP.utf8");    puts("\nIn Japanese locale:");    test(a3, u3, j3);}

输出:

In American locale:        '3' '三' '3'iswdigit 1    0   0jdigit:  0    0   0
 In Japanese locale:        '3' '三' '3'iswdigit 1    0   0jdigit:  0    0   1

参考

  • C11标准(ISO / IEC 9899:2011):

    • 7.30.2.1.5 iswdigit函数(p:449)

  • C99标准(ISO / IEC 9899:1999):

    • 7.25.2.1.5 iswdigit函数(p:395)

扩展内容

isdigit

检查一个字符是否是一个数字(功能)

| 用于iswdigit的C ++文档 |

ASCII 值  (十六进制)

字符

iscntrl  iswcntrl.

isprint  iswprint.

isspace  iswspace.

isblank  iswblank.

isgraph  iswgraph.

ispunct  iswpunct.

isalnum  iswalnum.

isalpha  iswalpha.

isupper  iswupper.

islower  iswlower.

isdigit  iswdigit.

isxdigit  iswxdigit.


0 - 8

0x00-0x08

控制码 (NUL, etc.)

≠0

0

0

0

0

0

0

0

0

0

0

0

9

0x09

tab (\t)

≠0

0

≠0

≠0

0

0

0

0

0

0

0

0

10 - 13

0x0A-0x0D

空格 (\n,\v,\f,\r)

≠0

0

≠0

0

0

0

0

0

0

0

0

0

14 - 31

0x0E-0x1F

控制码

≠0

0

0

0

0

0

0

0

0

0

0

0

32

0x20

space

0

≠0

≠0

≠0

0

0

0

0

0

0

0

0

33 - 47

0x21-0x2F

!"#$%&'()*+,-./

0

≠0

0

0

≠0

≠0

0

0

0

0

0

0

48 - 57

0x30-0x39

0123456789

0

≠0

0

0

≠0

0

≠0

0

0

0

≠0

≠0

58 - 64

0x3a-0x40

:;<=>?@

0

≠0

0

0

≠0

≠0

0

0

0

0

0

0

65 - 70

0x41-0x46

ABCDEF

0

≠0

0

0

≠0

0

≠0

≠0

≠0

0

0

≠0

71 - 90

0x47-0x5A

GHIJKLMNOPQRSTUVWXYZ

0

≠0

0

0

≠0

0

≠0

≠0

≠0

0

0

0

91 - 96

0x5B-0x60

[]^_` | 0 | ≠0 | 0 | 0 | ≠0 | ≠0 | 0 | 0 | 0 | 0 | 0 | 0 |













97 -102

0x61-0x66

abcdef

0

≠0

0

0

≠0

0

≠0

≠0

0

≠0

0

≠0

103-122

0x67-0x7A

ghijklmnopqrstuvwxyz

0

≠0

0

0

≠0

0

≠0

≠0

0

≠0

0

0

123-126

0x7B-0x7E

{|}~

0

≠0

0

0

≠0

≠0

0

0

0

0

0

0

127

0x7F

退格 (DEL)

≠0

0

0

0

0

0

0

0

0

0

0

0

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