I am not looking for a correction, just an explanation. In the snippet below, why am I getting the output as 2.000000?

#include <stdio.h>
#include <stdlib.h>

int main() {
    double static const val = 0x1P1;
    printf("%d\t%f\n", val, val);
    return EXIT_SUCCESS;
}

Shouldn’t this be equal to 11?

  • blackjacksepp@feddit.de
    0·
    9 months ago

    From the documentation (emphasis mine):

    If the floating literal begins with the character sequence 0x or 0X, the floating literal is a hexadecimal floating literal. Otherwise, it is a decimal floating literal.

    For a hexadecimal floating literal, the significand is interpreted as a hexadecimal rational number, and the digit-sequence of the exponent is interpreted as the (decimal) integer power of 2 by which the significand has to be scaled.

    double d = 0x1.4p3; // hex fraction 1.4 (decimal 1.25) scaled by 2^3, that is 10.0

    You can find the full documentation here: cppreference.com

    So in your example 0x1P1 means 116 * 2^(110) = 2