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之前被面试C语言经常问到如何判断系统是大端存储还是小端存储，自己想尽各种办法，又在百度上查各种奇葩方法。 最近发现大小端存储是由CPU本身架构决定的，不是由操作系统定的。像咱们平时使用的intel、AMD处理器都是小端存储（不知道人家有没有推出大端存储）。 Windows系统CPU类型定义头文件位置（以我的电脑为例）：C:\Program Files (x86)\Windows Kits\8.1\Include\um\winnt.h 从15019行到15048行，原定义如下： #define IMAGE_FILE_MACHINE_UNKNOWN 0
#define IMAGE_FILE_MACHINE_I386 0x014c // Intel 386.
#define IMAGE_FILE_MACHINE_R3000 0x0162 // MIPS little-endian, 0x160 big-endian
#define IMAGE_FILE_MACHINE_R4000 0x0166 // MIPS little-endian
#define IMAGE_FILE_MACHINE_R10000 0x0168 // MIPS little-endian
#define IMAGE_FILE_MACHINE_WCEMIPSV2 0x0169 // MIPS little-endian WCE v2
#define IMAGE_FILE_MACHINE_ALPHA 0x0184 // Alpha_AXP
#define IMAGE_FILE_MACHINE_SH3 0x01a2 // SH3 little-endian
#define IMAGE_FILE_MACHINE_SH3DSP 0x01a3
#define IMAGE_FILE_MACHINE_SH3E 0x01a4 // SH3E little-endian
#define IMAGE_FILE_MACHINE_SH4 0x01a6 // SH4 little-endian
#define IMAGE_FILE_MACHINE_SH5 0x01a8 // SH5
#define IMAGE_FILE_MACHINE_ARM 0x01c0 // ARM Little-Endian
#define IMAGE_FILE_MACHINE_THUMB 0x01c2 // ARM Thumb/Thumb-2 Little-Endian
#define IMAGE_FILE_MACHINE_ARMNT 0x01c4 // ARM Thumb-2 Little-Endian
#define IMAGE_FILE_MACHINE_AM33 0x01d3
#define IMAGE_FILE_MACHINE_POWERPC 0x01F0 // IBM PowerPC Little-Endian
#define IMAGE_FILE_MACHINE_POWERPCFP 0x01f1
#define IMAGE_FILE_MACHINE_IA64 0x0200 // Intel 64
#define IMAGE_FILE_MACHINE_MIPS16 0x0266 // MIPS
#define IMAGE_FILE_MACHINE_ALPHA64 0x0284 // ALPHA64
#define IMAGE_FILE_MACHINE_MIPSFPU 0x0366 // MIPS
#define IMAGE_FILE_MACHINE_MIPSFPU16 0x0466 // MIPS
#define IMAGE_FILE_MACHINE_AXP64 IMAGE_FILE_MACHINE_ALPHA64
#define IMAGE_FILE_MACHINE_TRICORE 0x0520 // Infineon
#define IMAGE_FILE_MACHINE_CEF 0x0CEF
#define IMAGE_FILE_MACHINE_EBC 0x0EBC // EFI Byte Code
#define IMAGE_FILE_MACHINE_AMD64 0x8664 // AMD64 (K8)
#define IMAGE_FILE_MACHINE_M32R 0x9041 // M32R little-endian
#define IMAGE_FILE_MACHINE_CEE 0xC0EE
Linux系统CPU类型定义头文件位置（以我的电脑为例）：/usr/include/elf.h 从173行到263行源代码如下： /* Legal values for e_machine (architecture). */
#define EM_NONE 0 /* No machine */
#define EM_M32 1 /* AT&T WE 32100 */
#define EM_SPARC 2 /* SUN SPARC */
#define EM_386 3 /* Intel 80386 */
#define EM_68K 4 /* Motorola m68k family */
#define EM_88K 5 /* Motorola m88k family */
#define EM_860 7 /* Intel 80860 */
#define EM_MIPS 8 /* MIPS R3000 big-endian */
#define EM_S370 9 /* IBM System/370 */
#define EM_MIPS_RS3_LE 10 /* MIPS R3000 little-endian */
#define EM_PARISC 15 /* HPPA */
#define EM_VPP500 17 /* Fujitsu VPP500 */
#define EM_SPARC32PLUS 18 /* Sun's "v8plus" */
#define EM_960 19 /* Intel 80960 */
#define EM_PPC 20 /* PowerPC */
#define EM_PPC64 21 /* PowerPC 64-bit */
#define EM_S390 22 /* IBM S390 */
#define EM_V800 36 /* NEC V800 series */
#define EM_FR20 37 /* Fujitsu FR20 */
#define EM_RH32 38 /* TRW RH-32 */
#define EM_RCE 39 /* Motorola RCE */
#define EM_ARM 40 /* ARM */
#define EM_FAKE_ALPHA 41 /* Digital Alpha */
#define EM_SH 42 /* Hitachi SH */
#define EM_SPARCV9 43 /* SPARC v9 64-bit */
#define EM_TRICORE 44 /* Siemens Tricore */
#define EM_ARC 45 /* Argonaut RISC Core */
#define EM_H8_300 46 /* Hitachi H8/300 */
#define EM_H8_300H 47 /* Hitachi H8/300H */
#define EM_H8S 48 /* Hitachi H8S */
#define EM_H8_500 49 /* Hitachi H8/500 */
#define EM_IA_64 50 /* Intel Merced */
#define EM_MIPS_X 51 /* Stanford MIPS-X */
#define EM_COLDFIRE 52 /* Motorola Coldfire */
#define EM_68HC12 53 /* Motorola M68HC12 */
#define EM_MMA 54 /* Fujitsu MMA Multimedia Accelerator*/
#define EM_PCP 55 /* Siemens PCP */
#define EM_NCPU 56 /* Sony nCPU embeeded RISC */
#define EM_NDR1 57 /* Denso NDR1 microprocessor */
#define EM_STARCORE 58 /* Motorola Start*Core processor */
#define EM_ME16 59 /* Toyota ME16 processor */
#define EM_ST100 60 /* STMicroelectronic ST100 processor */
#define EM_TINYJ 61 /* Advanced Logic Corp. Tinyj emb.fam*/
#define EM_X86_64 62 /* AMD x86-64 architecture */
#define EM_PDSP 63 /* Sony DSP Processor */
#define EM_FX66 66 /* Siemens FX66 microcontroller */
#define EM_ST9PLUS 67 /* STMicroelectronics ST9+ 8/16 mc */
#define EM_ST7 68 /* STmicroelectronics ST7 8 bit mc */
#define EM_68HC16 69 /* Motorola MC68HC16 microcontroller */
#define EM_68HC11 70 /* Motorola MC68HC11 microcontroller */
#define EM_68HC08 71 /* Motorola MC68HC08 microcontroller */
#define EM_68HC05 72 /* Motorola MC68HC05 microcontroller */
#define EM_SVX 73 /* Silicon Graphics SVx */
#define EM_ST19 74 /* STMicroelectronics ST19 8 bit mc */
#define EM_VAX 75 /* Digital VAX */
#define EM_CRIS 76 /* Axis Communications 32-bit embedded processor */
#define EM_JAVELIN 77 /* Infineon Technologies 32-bit embedded processor */
#define EM_FIREPATH 78 /* Element 14 64-bit DSP Processor */
#define EM_ZSP 79 /* LSI Logic 16-bit DSP Processor */
#define EM_MMIX 80 /* Donald Knuth's educational 64-bit processor */
#define EM_HUANY 81 /* Harvard University machine-independent object files */
#define EM_PRISM 82 /* SiTera Prism */
#define EM_AVR 83 /* Atmel AVR 8-bit microcontroller */
#define EM_FR30 84 /* Fujitsu FR30 */
#define EM_D10V 85 /* Mitsubishi D10V */
#define EM_D30V 86 /* Mitsubishi D30V */
#define EM_V850 87 /* NEC v850 */
#define EM_M32R 88 /* Mitsubishi M32R */
#define EM_MN10300 89 /* Matsushita MN10300 */
#define EM_MN10200 90 /* Matsushita MN10200 */
#define EM_PJ 91 /* picoJava */
#define EM_OPENRISC 92 /* OpenRISC 32-bit embedded processor */
#define EM_ARC_A5 93 /* ARC Cores Tangent-A5 */
#define EM_XTENSA 94 /* Tensilica Xtensa Architecture */
#define EM_ALTERA_NIOS2 113 /* Altera Nios II */
#define EM_AARCH64 183 /* ARM AARCH64 */
#define EM_TILEPRO 188 /* Tilera TILEPro */
#define EM_MICROBLAZE 189 /* Xilinx MicroBlaze */
#define EM_TILEGX 191 /* Tilera TILE-Gx */
#define EM_NUM 192
/* If it is necessary to assign new unofficial EM_* values, please
pick large random numbers (0x8523, 0xa7f2, etc.) to minimize the
chances of collision with official or non-GNU unofficial values. */
#define EM_ALPHA 0x9026
万恶的面试官，大小端存储是由cpu硬件定的，非要我们写个C程序获取系统的大小存储，cpu类型一看不就知道是大端存储，还是小端存储。 | 
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