C功能模块集锦

1. offsetof

#include <stddef.h>

size_t offsetof(type, member);

The macro offsetof() returns the offset of the field member from the start of the structure type.

2. float和int转换

最简单的方法是采用union。

    float ff = 123456.0;
    union{int i; float f;} conv;
    conv.f = ff;
    aa[0] = (unsigned short)conv.i;
    aa[1] = (unsigned short)(conv.i >> 16);
    printf("%X, %X, %X
", conv.i, aa[0], aa[1]);