bitset size() in C++ STL

bitset::size() is a built-in STL in C++ which returns the total number of bits. 

Syntax: 

bitset_name.size()

Parameter: The function accepts no parameter. 

Return Value: The function returns an integral value which signifies the number of bits. It eventually returns the size that has been given while initializing the bitset.

Below programs illustrate the bitset::size() function. 

Program 1: 

C++

// C++ program to illustrate the
// bitset::size() function
// when input is a string

#include <bits/stdc++.h>
using namespace std;

int main()
{
    // initialization of the bitset string
    bitset<4> b1(string("1100"));
    bitset<6> b2(string("010010"));

    // prints the size i.e.,
    // the number of bits in "1100"
    cout << "The number of bits in " << b1
         << " is " << b1.size() << endl;

    // prints the size i.e.,
    // the number of bits in  "010010"
    cout << "The number of bits in " << b2
         << " is " << b2.size() << endl;

    return 0;
}

Output:

The number of bits in 1100 is 4
The number of bits in 010010 is 6

Program 2: 

C++

// C++ program to illustrate the
// bitset::size() function
// when input is a number

#include <bits/stdc++.h>
using namespace std;

int main()
{
    // initialization of the bitset string
    bitset<3> b1(5);
    bitset<5> b2(17);

    // prints the size i.e.,
    // the number of bits in 5
    cout << "The number of bits in " << b1
         << " is " << b1.size() << endl;

    // prints the size i.e.,
    // the number of bits in 17
    cout << "The number of bits in "
         << b2 << " is " << b2.size() << endl;

    return 0;
}

Output:

The number of bits in 101 is 3
The number of bits in 10001 is 5