I would like to ask you a question in C language.

int main(void) { double x; x = (1.0e17 + 5.0) - 1.0e17; printf("%lf \n", x); return 0; }

int main(void) { double x; x = (1.0e16 + 5.0) - 1.0e16; printf("%lf \n", x); return 0; }

int main(void) { double x; x = (1.0e15 + 5.0) - 1.0e15; printf("%lf \n", x); return 0; }

When EXP is on the 17th, 0 will be printed When EXP is 16, 4 is printed out When the EXP is 15, 5 is output.

It seems to be output normally when it is EXP15, but why does the value come out weird from above 16?