C++实现IPv4地址类：Bitset初始化与IP解析完善需求

Hey there! Let's get that bitset<8> bits[4] member set up correctly using the parsed octets from your IPv4 input.

Quick Background #

Your current code already does a great job parsing the user's IP into the arr[4] array of unsigned char octets. Since each octet is an 8-bit value, initializing the bitset<8> array is straightforward—std::bitset has a constructor that takes an integer type, which we can use directly with each element of arr.

Updated Constructor Code #

Here's how to modify your constructor to initialize the bitset array properly:

#include <iostream>
#include <bitset>
#include <cstring>

class Address { 
private : 
    unsigned char arr[4] = {0}; 
    std::bitset<8> bits[4];
public : 
    Address(){ 
        char ip[50]; 
        std::cout << "Enter your IP ADDRESS: "; 
        std::cin >> ip; 

        int k = 0;
        unsigned char current_octet = 0;
        
        for(int i = 0; ip[i] != '\0'; ++i){ 
            if(ip[i] != '.'){ 
                // Convert character digit to integer value
                current_octet = current_octet * 10 + (ip[i] - '0');
            } else { 
                // Store the parsed octet and initialize its bitset
                arr[k] = current_octet;
                bits[k] = std::bitset<8>(current_octet);
                current_octet = 0;
                ++k; 
            }
        }
        // Handle the final octet (after the last dot)
        arr[k] = current_octet;
        bits[k] = std::bitset<8>(current_octet);
    }

    // Optional: Method to display the bits for testing
    void printBitRepresentation() const {
        for(int i = 0; i < 4; ++i){
            std::cout << bits[i];
            if(i != 3) std::cout << ".";
        }
        std::cout << "\n";
    }
};

Key Notes #

• Initialize as you parse: By setting bits[k] right after we finish parsing an octet (when we hit a '.'), we ensure we don't skip any values. We also handle the final octet outside the loop since there's no trailing dot.
• Readable conversions: Using ip[i] - '0' instead of ip[i] - 48 makes the code easier to read—it clearly shows we're converting a character digit to its integer equivalent.
• Verification method: The printBitRepresentation() function lets you confirm the bitset is working. For example, inputting 10.0.0.1 will output 00001010.00000000.00000000.00000001.
• Input validation note: Your current parser assumes valid IP inputs. For robustness, you might want to add checks later (like ensuring octets are between 0-255, no non-digit characters, etc.), but that's separate from the bitset task.

Alternative: Initialize in a Separate Loop #

If you prefer to separate parsing and bitset setup, you can add this loop at the end of your constructor (after parsing all octets into arr):

for(int i = 0; i < 4; ++i){
    bits[i] = std::bitset<8>(arr[i]);
}

This is equally effective—pick whichever style fits your coding preference.

内容的提问来源于stack exchange，提问作者Nagato