Approach 1: Using stoi()

The easiest way to convert a bitset to an integer is to use the std::stoi() function, which converts a string to an integer. Since bitset has a built-in to_string() method, we can convert the bitset to a string and then use stoi() to convert it to an integer.

#include <iostream>
#include <bitset>
#include <string>

int main() {
    std::bitset<8> bits("10101010");
    int result = std::stoi(bits.to_string(), nullptr, 2);
    std::cout << "Converted integer: " << result << std::endl;
    return 0;
}

In the above code, we create a bitset named bits with a size of 8 bits and initialize it with the binary value “10101010”. We then use bits.to_string() to convert the bitset to a string. Finally, std::stoi() is used to convert the string to an integer by passing the base value 2 to indicate binary.

Approach 2: Using a Loop

A more manual approach to converting a bitset to an integer is to use a loop and bit manipulation. We iterate through each bit of the bitset from the most significant bit to the least significant bit, multiplying each bit by 2 raised to the corresponding power.

#include <iostream>
#include <bitset>

int main() {
    std::bitset<8> bits("10101010");
    int result = 0;
    
    for (int i = bits.size() - 1; i >= 0; i--) {
        if (bits[i]) {
            result += (1 << (bits.size() - 1 - i));
        }
    }
    
    std::cout << "Converted integer: " << result << std::endl;
    return 0;
}

In this code, we declare a result variable to store the converted integer. We iterate through each bit of the bitset using a loop, starting from the most significant bit and going towards the least significant bit. If a bit is 1, we calculate its value by using the bitwise left shift operator << to shift 1 by the corresponding power. The shifted value is then added to the result. Finally, we output the result.

Conclusion

In this blog post, we covered two approaches to convert a C++ bitset to an integer. The first approach used the std::stoi() function to convert the bitset to a string and then convert the string to an integer. The second approach used a loop and bit manipulation to manually convert the bitset to an integer. Depending on your specific use case and performance requirements, you can choose the approach that best suits your needs.

#cplusplus #bitset #conversion