32位机各数据类型取值范围

CHAR_BIT:  8

CHAR_MAX:  127

CHAR_MIN:  -128

SCHAR_MAX: 127

SCHAR_MIN: -128

UCHAR_MAX: 255

SHRT_MAX:  32767

SHRT_MIN:  -32768

USHRT_MAX: 65535

INT_MAX:   2147483647

INT_MIN:   -2147483648

UINT_MAX:  4294967295

LONG_MAX:  9223372036854775807

LONG_MIN:  -9223372036854775808

ULONG_MAX: 18446744073709551615

LLONG_MAX: 9223372036854775807

 

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2 ^ 8 = 256

2^16 = 65535                                         6w+

2^32 = 4294967295            　　　　　　   42亿

2^64 = 18446744073709551615              2千亿亿

=====================================

我的挫机器做10亿次空循环需要的时间:

Time to do 1073741823 empty loops is 3.342565 seconds

 

代码:

clock_t start=clock();
int i = 0;
for ( ; i < INT_MAX/2; i++);
clock_t finish = clock();
float duration = (double)(finish - start) / CLOCKS_PER_SEC;
printf("Time to do %d empty loops is %f seconds\n", i, duration);