I'm not sure how to properly explain this, but I'm looking for a way to automatically set the size or number of the bitset<size> automatically
Example
cout << bitset<8>(7) << endl;
outputs with a fixed number of bits
0000 0111
I want to automatically output with variable number of bits like outputting 111 and 11001 instead of using the fixed bits.
Basically I want to cut the 0's in front when it's not used
That's actually two questions in one. The first is how to trim the output a given bitset (i.e. remove the leading 0's), the second how to reduce the output to a given size.
As your interested only in the ostream output, for both it should be quite appropriate to use the bitset::to_string() conversion function, followed by an application of string::substr.
With this, for your example -- where it seems you want to retain 7 bits -- you would get:
std::cout << std::bitset<8>{}.to_string().substr(1) << std::endl; //removes the first bit
You can combine that with a method to find the first set bit in order to construct the trim function.
int main() {
int n;
cin >> n;
bitset<64> n2(n);
cout << n2.to_string().substr(64-n2._Find_first()-1) << endl;
}
std::bitset::_Find.first will find the index of the first on bit.
We convert n2 to a string, we then find the substring of the string from the index where we find the most significant bit subtracted by the total length - 1, therefore giving us the required result.
Testcase:
256
100000000
