计算由十六进制浮点数表示的值

Question

Can someone explain how we calculate the value of Hexadecimal Floating point constant. I was reading a book and found 0x0.3p10 represents the value 192.

Answer 1

The exponent is still expressed in decimal, but the base is two, and the mantissa is in hex.

So 0.3P10 is (3 × 16 ⁻¹ ) × 2 ¹⁰ , which is 3/16 × 2 ¹⁰ , which is 3 × 2 ⁶ = 192.

Each hex digit of the mantissa gobbles up four units of exponent, since 16 = 2 ⁴ .