If char c = 0x80, why does printf(“%d\n”, c << 1) output -256?

Question

#include
int main(void)
{
  char c = 0x80;
  printf(\"%d\\n\", c << 1);
  return 0;
}

The output is -256 in this

Answer 1

I wonder why your compiler do not complain with a warning that 0x80 does not fit in char, which on your platform can represent only values from -0x80 to 0x7F.

Try this piece of code:

 #include 
 #include 
 #include 

 int main() {
      printf("char can represent values from %d to %d.\n", CHAR_MIN, CHAR_MAX);
      return EXIT_SUCCESS;
 }

Your situation is called OVERFLOW.