1. print double type value to binary/hexadecimal expression in c++ 2. double parser for converting binary to double in Python

double.cpp

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <stack>
#include <bitset>
#include <cstdlib>
#include <cmath>
#include <set>
#include <list>
#include <deque>
#include <map>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <assert.h>
using namespace std;

typedef long long ll;
const int INF = 0x7fffffff;
const double eps = 1e-8;

int main()
{
    double num = 1.00;
    unsigned long long v = num;
    memcpy(&v, &num, sizeof(num));

    cout << hex << v << endl;

    return 0;
}

double.py

import struct

def double_parser(d):
    sign = 1 if d[0] == '0' else -1
    
    e = 2 ** (int(d[1:12], 2) - 1023)
    
    f = 1 + sum([2 ** -(i+1) if d[12 + i] == '1' else 0 for i in range(52)])
    
    if d[1:12] == "1" * 11:
        if f == 1:
            return "INF" if sign == 1 else "-INF"
        else:
            return "NaN"
    
    return sign * e * f
    
def float_to_bin(value):  # For testing.
    """ Convert float to 64-bit binary string. """
    [d] = struct.unpack(">Q", struct.pack(">d", value))
    return '{:064b}'.format(d)

import random 

for i in range(50):
    r = random.uniform(-1e10, 1e10)
    assert double_parser(float_to_bin(r)) == r, f'test {r} failed'

assert double_parser("0 11111111111 0000000000000000000000000000000000000000000000000000".replace(" ", "")) == "INF"
assert double_parser("1 11111111111 0000000000000000000000000000000000000000000000000000".replace(" ", "")) == "-INF"
assert double_parser("0 11111111111 0000000000000000000000000000000000000000000000000001".replace(" ", "")) == "NaN"
assert double_parser("0 11111111111 1000000000000000000000000000000000000000000000000001".replace(" ", "")) == "NaN"
assert double_parser("0 11111111111 1111111111111111111111111111111111111111111111111111".replace(" ", "")) == "NaN"

print("Accpet")

• float - wiki
• double - wiki
• Double(IEEE754) Online Parser