title: convert 64-bit binary string representation of a double number back to double number in c++
body: <p>I have a IEEE754 Double precision 64-bit binary string representation of a double number.
  example : double value = 0.999;
  Its binary representation is "0011111111101111111101111100111011011001000101101000011100101011"</p>
  
  <p>I want to convert this string back to a double number in c++.
  I dont want to use any external libraries or .dll's as my program would operate in any platform.</p>