What is -(-128) for signed single byte char in C?

Question

My little program:

#include 

int main() {
    signed char c = -128;
    c = -c;
    printf(\"%d\", c);
    return 0;
}

prin

Answer 1

Note: -128 in 2's complement is 1000 0000 (in one byte) and 128 is also 1000 0000 . If you do char c = 128 and print it it will be -128 because of the following reason:

A char variable = 128 value stores in memory as follows.

MSB
+----+----+----+---+---+---+---+---+
|  1 |  0 | 0  | 0 | 0 | 0 | 0 | 0 |   
+----+----+----+---+---+---+---+---+
   7    6   5    4   3   2   1   0  

Now,

1. this value will be interpreted as negative value because MSB is 1,

2. to print magnitude of this -ve number 2's complement needed, that is also 128 in one byte so output is: -128

   2's complement:

     1000 0000
   
     0111 1111  1's complement 
   + 0000 0001 
    -----------
     1000 0000  2's complement   
   
    Magnitude = 128 
    So in one byte 128 == -128