Unsigned and signed shift:logical shift and arithmetic shift

In C, we usually use left shift and right shift operation << and >> to operate multiple / divide to variable with power of 2,ex: 4<<2  = 16

But when we use the signed variable and the shift operation we must consider the singed bit.See the below example code.

	int 8_t b = -10; // b = 0xf6 for 2's complement
	b = b << 1; // b=0xec
	b = b >> 1; // Now b = 0x76 and for demical b = 118 unexpect ouput
	// The correct way to do that operation
	b = b&0x80 | b>>1;// b = 0xf6 for demical b = 10

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Since the C language support the arithmetic left shift and logic right shift,  we must consider the signed bit to  avoid some bug in code.



Ref:
     1.Logical Vs. Arithmetic Shift
     2.C语言中的逻辑右移和算术左移