十六进制字符串转换为浮点数

如何在Python中将以下十六进制字符串转换为float（单精度32位）？

"41973333" -> 1.88999996185302734375E1
"41995C29" -> 1.91700000762939453125E1
"470FC614" -> 3.6806078125E4

方法一

>>> import struct
>>> struct.unpack('!f', '41973333'.decode('hex'))[0]
18.899999618530273
>>> struct.unpack('!f', '41995C29'.decode('hex'))[0]
19.170000076293945
>>> struct.unpack('!f', '470FC614'.decode('hex'))[0]
36806.078125

方法二

from ctypes import *

def convert(s):
    i = int(s, 16)                   # convert from hex to a Python int
    cp = pointer(c_int(i))           # make this into a c integer
    fp = cast(cp, POINTER(c_float))  # cast the int pointer to a float pointer
    return fp.contents.value         # dereference the pointer, get the float

print convert("41973333")    # returns 1.88999996185302734375E1

print convert("41995C29")    # returns 1.91700000762939453125E1

print convert("470FC614")    # returns 3.6806078125E4

方法三

import struct 

testcases = {
"41973333": 1.88999996185302734375E1,
"41995C29": 1.91700000762939453125E1,
"470FC614": 3.6806078125E4,
}

def hex2float(s):
    bins = ''.join(chr(int(s[x:x+2], 16)) for x in range(0, len(s), 2))
    return struct.unpack('>f', bins)[0]

for s in testcases:
  print(hex2float(s), testcases[s])

#18.8999996185 18.8999996185
#19.1700000763 19.1700000763
#36806.078125 36806.078125

合集

import struct
import ctypes

def f2h(s):
    fp = ctypes.pointer(ctypes.c_double(s))
    cp = ctypes.cast(fp, ctypes.POINTER(ctypes.c_longlong))
    return hex(cp.contents.value)

def float_to_hex(f):
    return hex(struct.unpack('<I', struct.pack('<f', f))[0])

def float2hex(s):
    fp = ctypes.pointer(ctypes.c_float(s))
    cp = ctypes.cast(fp,ctypes.POINTER(ctypes.c_long))
    return hex(cp.contents.value)

def h2f(s):
    cp = ctypes.pointer(ctypes.c_longlong(s))
    fp = ctypes.cast(cp, ctypes.POINTER(ctypes.c_double))
    return fp.contents.value

def hex_to_float(h):
    i = int(h,16)
    return struct.unpack('<f',struct.pack('<I', i))[0]

def hex2float(h):
    i = int(h,16)
    cp = ctypes.pointer(ctypes.c_int(i))
    fp = ctypes.cast(cp,ctypes.POINTER(ctypes.c_float))
    return fp.contents.value

if __name__ == '__main__':
    f = [1.5,-1.5,3.5,-3.5]
    h = []
    for i in f:
        print(f2h(i),"   |   ",float_to_hex(i),"   |   ",float2hex(i))
        h.append(float_to_hex(i))
    print(h)
    for i in h :
        print(h2f(i),"   |   ",hex_to_float(i),"   |   ",hex2float(i))

学习来源