two_state_machine.c

#include <stdio.h>

typedef enum {
	ST_RADIO,
	ST_CD
} STATES;

typedef enum {
	EVT_MODE,
	EVT_NEXT
} EVENTS;

int main()
{
	STATES state = ST_RADIO;
	int stationNumber = 0;
	int trackNumber = 0;
	int event = 0;

	while(1) {
		printf("current state is %s\n", (state == ST_RADIO)?"ST_RADIO":"ST_CD");
		scanf("%d", &event);
		switch (state) {
			case ST_RADIO:
				switch (event) {
					case EVT_MODE:
						state = ST_CD;
						break;
					case EVT_NEXT:
						stationNumber++;
						break;
					default: 
						break;
				}
				break;
			case ST_CD:
				switch (event) {
					case EVT_MODE:
						state = ST_RADIO;
						break;
					case EVT_NEXT:
						trackNumber++;
						break;
					default:
						break;
				}
				break;
			default:
				break;
		}
	}
}

关键是在输出当前状态时，(state == ST_RADIO)?"ST_RADIO":"ST_CD")的写法

其中的"ST_RADIO"和"ST_CD"是两个字符串常量，在编译时就已经确定了，在静态存储区中