C语言char的运算，求指点
[code=C/C++][/code]int main()
{
char x = 127;

unsigned char a = x + 1;
unsigned short b = x + 1;
unsigned long c = x + 1;
x=x+1;//x=-128?
char d = x+1;//d=-127?
char e = x-1;//e=127?
printf("0x%x, 0x%x, 0x%x, 0x%x", a, b, c,d);
getchar();
return 0;
}


上面问号处求详细解释一下运算原理...............

[解决办法]
char的取值范围是-128到127
x=127;x=x+1;127+1相当于-128
[解决办法]
char的取值范围是-128到127
x=127;x=x+1;127+1相当于-128