三种方式获得int的size

size_t getIntSize() {
	int a[2];
	return (char*)(a+1) - (char*)a;
}

size_t getIntSize2() {
	int n = 0;
	int i = 1;
	do {
		i = i << 8;
		n++;
	} while (i != 0);
	return n;
}

size_t getIntSize3() {
	union {
		short ival;
		char cval[8];
	} v;
	for (int i = 0; i < 8; ++i) {
		v.cval[i] = 1;
	}
	v.ival = 0;
	int n = 0;
	int i = 0;
	while (!v.cval[i++]) {
		n++;
	}
	return n;
}