IEEE754ToDec.py

# this program converts a floating point number from binary to decimal
# sign mantissa * 2**(exponent)

sign = 0
exponent = '10100'
mantissa = '0110101110'


# convert binary to decimal
def bin2dec(n):
    sum, x = 0, 1
    for i in reversed(n):
        if i == '1':
            sum += x
        x*=2
    return sum


# convert mantissa to dec
def mantissa2dec(m):
    sum, x = 0, 1.0

    for i in m:
        x /= 2
        if i == '1':
            sum += x
    return 1+sum



bias = 2**(len(exponent)-1)-1       # bias = [2**(number of bits in exponent - 1)] -1
mantissa = mantissa2dec(mantissa)   # mantissa converted to decimal
exponent = bin2dec(exponent) - bias # exponent - bias

number = mantissa * 2**exponent     # mantissa * 2**(exponent)
if sign: number *= -1               # make the number negative depending on the sign

print(number)