求助:CVAVR stdio.h下的printf()不能打印字符串

shiming456

如题,输出字符,十进制,十六进制,浮点数是没问题的
    printf("currently state:%c\n",'a');
    printf("currently state:%d\n",'a');
    printf("currently state:%x\n",'a');
    printf("currently state:%2.3f\n",3.8);
    printf("currently state:%2.3e\n",4.5);
但是字符串没办法输出
    printf("currently state:%s\n","string");

定义指针,无论是指向flash还是ram都没输出
//    char *str="test";   
    flash char *str="test";
printf("currently state:%s\n",str);     这样仍不行

如果定义一个数组,输出结果就正常
   uchar str[]="test";
   printf("currently state:%s\n",str);

在使用puts()和putsf()也会有同样的问题,实参用指针就出错.
不知道问题出在哪,是我的用法不对吗? 请高手指教