#include <iostream>
#include <cstdint>
#include <time.h>
using namespace std;
 
#define ID_LENGTH 8  // 設定BIT長度
 
void foo(uint32_t id, char* disp)
{
	if(disp == NULL)  // 避免NULL Pointer
		return;
	uint32_t bit_mask = (1 << (ID_LENGTH) - 1);  // 位元檢查遮罩
	for(int i = 0; i < ID_LENGTH; i++)
	{
		disp[i] = ((id & bit_mask) == bit_mask)?'1':'0'; // 這一行等價於下面的程式碼
		/*
		if((id & bit_mask) == bit_mask)
		    disp[i] = '1';
		else
			disp[i] = '0'
		*/
		bit_mask >>= 1;  // 位移一次檢查遮罩，檢查下一位元
	}
}
 
 
int main() {
	char id_display[ID_LENGTH + 1] = {0};      // 設定字串陣列長度，+1是為了放結束字元
	srand(time(NULL));
	for(int i = 0; i < 10; i++)
	{
		uint32_t id = (uint32_t)(rand() % 7 + 1);  // 隨機生成一個ID
		foo(id, id_display);                       // 字串處理
		printf("ID = %u, disp = %s\n", id, id_display);  // 顯示ID及字串處理結果
	}
	return 0;
}

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