如何在python中转换浮点数？

Question

How to convert floating point number to base-16 numbers, 8 hexadecimal digits per 32-bit FLP number in python?

eg : input = 1.2717441261e+20 output wanted : 3403244E

Answer 1

If you want the byte values of the IEEE-754 representation, the struct module can do this:

>>> import struct
>>> f = 1.2717441261e+20
>>> struct.pack('f', f)
'\xc9\x9c\xdc`'

This is a string version of the bytes, which can then be converted into a string representation of the hex values:

>>> struct.pack('f', f).encode('hex')
'c99cdc60'

And, if you want it as a hex integer, parse it as such:

>>> s = struct.pack('f', f).encode('hex')
>>> int(s, 16)
3382500448

To display the integer as hex:

>>> hex(int(s, 16))
'0xc99cdc60'

Note that this does not match the hex value in your question -- if your value is the correct one you want, please update the question to say how it is derived.

Answer 2

There are several possible ways to do so, but none of them leads to the result you wanted.

• You can code this float value into its IEEE binary representation. This leads indeed to a 32 bit number (if you do it with single precision). But it leads to different results, no matter which endianness I suppose:

   import struct struct.pack("<f", 1.2717441261e+20).encode("hex") # -> 'c99cdc60' struct.pack(">f", 1.2717441261e+20).encode("hex") # -> '60dc9cc9' struct.unpack("<f", "3403244E".decode("hex")) # -> (687918336.0,) struct.unpack(">f", "3403244E".decode("hex")) # -> (1.2213533295835077e-07,) 

• As the other one didn't fit result-wise, I'll take the other answers and include them here:

   float.hex(1.2717441261e+20) # -> '0x1.b939919e12808p+66' 

  Has nothing to do with 3403244E as well, so maybe you want to clarify what exactly you mean.

There are surely other ways to do this conversation, but unless you specify which method you want, no one is likely to be able to help you.

Answer 3

There is something wrong with your expected output :

import struct
input = 1.2717441261e+20
buf = struct.pack(">f", input)
print ''.join("%x" % ord(c) for c in struct.unpack(">4c", buf) )

Output :

60dc9cc9

Answer 4

Try float.hex(input) . This should convert a number into a string representing the number in base 16, and works with floats, unlike hex() . The string will begin with 0x however, and will contain 13 digits after the decimal point, so I can't help you with the 8 digits part.

Source: http://docs.python.org/2/library/stdtypes.html#float.hex

Answer 5

如果input已经是浮点数，请尝试使用float.hex(input) 。