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stringsNull-terminated wide stringsstrcatstrcat_sstrchrstrcmpstrcollstrcpystrcpy_sstrcspnstrerrorstrerrorlen_sstrerror_sStrings librarystrlenstrncatThread supportcall_oncecnd_broadcastcnd_destroycnd_initcnd_signalcnd_timedwaitcnd_waitmtx_destroymtx_initmtx_lockmtx_plainmtx_recursivemtx_timedmtx_timedlockmtx_trylockmtx_unlockonce_flagONCE_FLAG_INITthrd_busythrd_createthrd_currentthrd_detachthrd_equalthrd_errorthrd_exitthrd_jointhrd_nomemthrd_sleepthrd_successthrd_timedoutthrd_yieldThread support librarythread_localtss_createtss_deleteTSS_DTOR_ITERATIONStss_gettss_setType supportBoolean type support libraryFixed width integer typesFLT_EVAL_METHODFLT_ROUNDSmax_align_tNULLNumeric limitsoffsetofptrdiff_tsize_tType supportVariadic functionsVariadic functionsva_argva_copyva_endva_listva_start

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在头文件<math.h>中定义



typedef /*implementation defined*/ float_t


(自 C99)

typedef /*implementation defined*/ double_t


(自 C99)

float_t和double_t类型的浮点类型至少与float和double一样宽，并且double_t至少与float_t一样宽。 FLT_EVAL_METHOD的值决定了float_t和double_t的类型。

FLT_EVAL_METHOD

说明

0

float_t和double_t分别等价于float和double

1

float_t和double_t都相当于double

2

float_t和double_t都相当于long double

其他

float_t和double_t都是实现定义的

例

#include <float.h>#include <math.h>#include <stdio.h>
 int main(void){    printf("%d\n", FLT_EVAL_METHOD);    printf("%zu  %zu\n", sizeof(float),sizeof(float_t));    printf("%zu  %zu\n", sizeof(double),sizeof(double_t));    return 0;}

可能的输出：

04  48  8

参考

  • C11标准（ISO / IEC 9899：2011）：

    • 7.12 <math.h>（p：231）

  • C99标准（ISO / IEC 9899：1999）：

    • 7.12 <math.h>（p：212）

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