编译了一下普中官方给的代码,可是报了一堆一样的错误,有没有大神帮我解答一一下???
APP\RC522\RC522.c(276): warning: #68-D: integer conversion resulted in a change of sign
{ status = MI_ERR; }
APP\RC522\RC522.c(300): warning: #68-D: integer conversion resulted in a change of sign
{ status = MI_ERR; }
APP\RC522\RC522.c(311): warning: #514-D: pointless comparison of unsigned integer with a negative constant
if (status != MI_ERR)
APP\RC522\RC522.c(316): warning: #68-D: integer conversion resulted in a change of sign
{ return MI_ERR; }
APP\RC522\RC522.c(326): warning: #68-D: integer conversion resulted in a change of sign
{ status = MI_ERR; }
APP\RC522\RC522.c(338): warning: #550-D: variable "status" was set but never used
char status;
APP\RC522\RC522.c(516): warning: #68-D: integer conversion resulted in a change of sign
char status = MI_ERR;
APP\RC522\RC522.c(564): warning: #68-D: integer conversion resulted in a change of sign
{ status = MI_NOTAGERR; }
APP\RC522\RC522.c(582): warning: #68-D: integer conversion resulted in a change of sign
{ status = MI_ERR; }