• 转换规则如下

• 例如一个char型变量a,其值为-1，另一个unsigned char型变量b,将变量a的值赋给变量b,则变量b的值为255

	 char a;
	 unsigned char b;
	 a = -1;
	 b = a;
	 printf("b=%d\n",b);

• 一个unsigned char变量a，其值为255,分别赋值给char型变量b,int型变量c,则赋值后变量b为-1，变量c为255

    unsigned char a;
	char b;
	int c;
	a = 255;
	b = a;
	c = a;
	printf("b=%d,c=%d\r\n",b,c);

• 一个char型变量a,其值为-1，分别赋值给short变量b和unsigend short 变量c,则赋值后b的值为-1，c的值为65535

    char a;
	short b;
	unsigned short c;
	a = -1;
	b = a;
	c = a;
	printf("b=%d,c=%d\r\n",b,c);

• 一个unsgined short型变量a,其值为0x6587，分别赋值给unsinghed char变量b和变量c,则赋值后b的值为0x87，c的值为0xffffff87

    unsigned short a;
	unsigned char b;
	char c;
	a = 0x6587;
	b = a;
	c = (unsigned long)a;
	printf("b=0x%x,c=0x%x\r\n",b,c);

• 一个int型变量a，其值为-1，另一个unsigned int变量为b,其值为39，将变量a乘以100再除以变量b的值赋给int变量c,则c的值为110127364

   int a;
   unsigned int b;
   int c;
   a = -1;
   b = 39;
   c = a * 100 / b;
   printf("c=%d\r\n",c);

• 如果将上述的变量b的值使用常量39代替，则c的值为-2

   int a;
   int c;
   a = -1;
   c = a * 100 / 39;
   printf("c=%d\r\n",c);

• 如果将上述使用的常量改成39u，则c的值为110127364

   int a;
   int c;
   a = -1;
   c = a * 100 / 39u;
   printf("c=%d\r\n",c);

• 一个int型变量a，其值为-1，另一个unsigned int变量为b,其值为39，将变量a乘以100再除以强制转换变量b为int类型后的值赋给int变量c,则c的值为-2

   int a;
   unsigned int b;
   int c;
   a = -1;
   b = 39;
   c = a * 100 / (int)b;
   printf("c=%d\r\n",c);