The Problem

Let’s say we have a bitset of size n and we want to extend it to a larger size m, where m is greater than n. The challenge is to efficiently extend the bitset without losing any of its existing bits. For example, if n is 8 and m is 16, we want to extend the bitset from 0000 1111 to 0000 1111 0000 0000.

The Solution

To extend the size of a bitset by padding with zeros, we can follow these steps:

1. Create a new bitset of the desired size m.
2. Copy the existing bits from the original bitset to the corresponding positions in the new bitset. This can be done using a loop and the [] operator.
3. Initialize the remaining bits in the new bitset to zero.

Here’s an example implementation:

#include <bitset>
#include <iostream>

// Function to extend a bitset by padding with zeros
std::bitset<16> extendBitset(const std::bitset<8>& original, int newSize) {
    std::bitset<16> extendedBitset;
    int originalSize = original.size();

    // Copy bits from the original bitset to the extended bitset
    for (int i = 0; i < originalSize; i++) {
        extendedBitset[i] = original[i];
    }

    // Pad the remaining bits with zeros
    for (int i = originalSize; i < newSize; i++) {
        extendedBitset[i] = 0;
    }

    return extendedBitset;
}

int main() {
    std::bitset<8> originalBitset("00001111");
    std::bitset<16> extendedBitset = extendBitset(originalBitset, 16);

    std::cout << "Original Bitset: " << originalBitset << std::endl;
    std::cout << "Extended Bitset: " << extendedBitset << std::endl;

    return 0;
}

In the above code, we define a function called extendBitset that takes an original bitset and the desired new size as parameters. The function creates a new bitset of size m and then copies the original bits into the corresponding positions in the new bitset. Finally, it pads the remaining bits with zeros. The main function demonstrates its usage by extending a bitset of size 8 to a size of 16.

Conclusion

By following the steps outlined in this blog post, we can extend the size of a bitset in C++ by padding it with zeros. This technique allows us to dynamically increase the size of a bitset without losing any of its existing bits.