Question

STC51单片机用printf()函数输出数字到串口，

unsigned char num = 1;
printf("num = %d",num);
结果为 num = 259
unsigned int num = 1;
printf("num = %d",num);
结果为 num = 1

为什么会这样

Answer 1

查C51关于printf的帮助文档：

%d 是处理int数据的，如果是char的看这句：The optional characters b or B may immediately precede the type character to
respectively specify char types for d, i, u, o, x, and X.

也就是要改为这样：printf("num = %bd",num);

Answer 2

貌似51单片机对printf的参数%d识别方式有点小小的问题，解决方法见链接。

网页链接