std :: bitset中的可变位长<size>

Question

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

Answer 1

That's actually two questions in one. The first is how to trim the output a given bitset (ie 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.