C++ Bitset::any() Function

The C++ function std::bitset::any() checks whether at least one bit of the current bitset object is set (bits with value 1) or not.

The any() function takes no arguments and returns a boolean value "true" if a single bit is set to 1; otherwise "false". It has multiple applications, such as finding bitsets with non-zero values and optimizing loops by skipping bitsets having no set bits.

The bitset class is a container that represents a fixed-size sequence of bits. Each bit in the bitset can have a value of either 0 or 1. The bitset class provides a number of member functions to manipulate individual bits of the bitset.

Syntax

Following is the syntax for std::bitset::any() −

bool any() const;

Parameters

It does not accept any parameter.

Return value

Returns boolean true or false.

Example 1

The following example shows the usage of std::bitset::any() using two bitsets.

Here, we are creating two bitsets "b" and "mask" of size "4" with the binary value "0000" and "1001" respectively. Then, we are checking if any bit of "b" is set using the any() function. We are then doing a bitwise OR operation between "b" and "mask", and checking again if any bit of "b" is set using the any() function.

#include <iostream>
#include <bitset>
using namespace std;

int main() {
   bitset<4> b("0000");
   bitset<4> mask("1001");
   if (b.any())
      cout << "At least one bit of b is set" << endl;
   else
      cout << "None of the bits of b are set" << endl;
   b |= mask;
   if (b.any())
      cout << "At least one bit of b is set" << endl;
   else
      cout << "None of the bits of b are set" << endl;
   return 0;
}

Output

Let us compile and run the above program, this will produce the following result −

None of the bits of b are set
At least one bit of b is set

Example 2

Here, we are using the any() function to check if any bit is set.

In the following example, we are creating a bitset "b" of size "5" with the binary value "00100". We are then using the any function() on "b" to check if at least one bit is set.

#include <iostream>
#include <bitset>
using namespace std;

int main() {
   bitset<5> b("00100");
   if (b.any())
      cout << "At least one bit of b is set" << endl;
   else
      cout << "None of the bits of b are set" << endl;
   return 0;
}

Output

If we run the above code it will generate the following output −

At least one bit of b is set

Example 3

In here, we are using the any() on a default bitset.

In the following example, we are creating a default bitset (value of all the bits is 0) "b" of size "4". We are then checking if any bit of "b" is set using the any() function.

#include <iostream>
#include <bitset>
using namespace std;

int main() {
   bitset<4> b;
   // default bitset will have default value of 0
   cout << "Binary value of b is " << b << endl;
   if (b.any())
      cout << "At least one bit of b is set" << endl;
   else
      cout << "None of the bits of b are set" << endl;
   return 0;
}

Output

Following is the output of the above code −

Binary value of b is 0000
None of the bits of b are set

Example 4

Here, we are creating a bitset "b" of size "4" with the binary value "1110". We are then performing a bitwise NOT operation on "b" and using the any() function to check if "b" has at least one bit set.

#include <iostream>
#include <bitset>
using namespace std;

int main() {
   bitset<4> b("1110");
   b = ~b;
   cout << "Binary value of b is " << b << endl;
   if (b.any())
      cout << "At least one bit of b is set" << endl;
   else
      cout << "None of the bits of b are set" << endl;
   return 0;
}

Output

Output of the above code is as follows −

Binary value of b is 0001
At least one bit of b is set