#define offsetof(type, member) /*implementation-defined*/ |
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宏 offsetof 展开成 size_t 类型的整数常量表达式,其值为从指定类型对象起始到其指定成员的偏移,若填充存在则包含之。
示例
#include <stdio.h>
#include <stddef.h>
struct S {
char c;
double d;
};
int main(void)
{
printf("the first element is at offset %zu\n", offsetof(struct S, c));
printf("the double is at offset %zu\n", offsetof(struct S, d));
}
可能的输出:
the first element is at offset 0
the double is at offset 8
参阅
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sizeof 运算符返回的无符号整数类型 (typedef) |