C++ Bitset::operator|= Function

The C++ std::bitset::operator|= is a compound assignment operator that performs a bitwise OR operation on the current bitset object.

The bitwise OR operator is a binary operator that performs a bitwise OR operation between the bits of two operands. It returns a value where each bit is set to 1 if either the corresponding bit of the left operand or the corresponding bit of the right operand is 1. Otherwise, the bit is set to 0.

The compound assignment operators are formed by combining a bitwise operator with the assignment operator (=), resulting in a new operator that performs the bitwise operation and assigns the result to the left operand.

Syntax

Following is the syntax for std::bitset::operator|= −

bitset& operator|= (const bitset& other);

Parameters

other − Another bitset object.

Return value

Returns this pointer.

Example 1

The following example shows the usage of std::bitset::operator|= using two bitsets of the same size.

Here, we are creating two bitsets with 4 bits each, setting the first bitset "b" to the binary value "1010", and the second bitset "mask" to the binary value "0101". Then we are performing a bitwise|= operation between them to set each bit in "b" to 0 if the corresponding bit in "mask" is 0, and leave it unchanged if the corresponding bit in "mask" is 1.

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

int main(void) {
   bitset<4> b("1010");
   bitset<4> mask("0101");
   b |= mask;
   cout << b << endl;
   return 0;
}

Output

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

1111

Example 2

Here, we are using a bitset and an integer to perform a bitwise OR operation.

In the following example, we are creating a bitset of size "8" with the binary value "11001100", and an integer "num" with the binary value "00111010". Then we use the |= operator and store the result back in bits.

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

int main(void) {
   bitset<8> bits("11001100");
   int num = 0b00111010;
   bits |= num;
   cout << bits << endl;  
   return 0;
}

Output

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

11111110

Example 3

Now, we are trying to perform a bitwise OR operation on the bitset with itself. We are creating a bitset with size "3" with the binary value "110". Then we use the |= operator and print the result in bits.

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

int main(void) {
   bitset<3> bits("110");
   bits |= bits;
   cout << bits << endl;  
   return 0;
}

Output

Following is an output of the above code −

110

Example 4

In here, we are using multiple (chaining) bitwise OR operations.

In the following example, we are creating three bitsets "a", "b", and "c" with the binary values "1010", "0011", and "1111" respectively. Then we use the |= operator to first perform a bitwise OR operation on "b" and "c", and then on "a". The values of "a" and "b" are both modified during this process.

#include <iostream>
#include <bitset>

int main() {
   std::bitset<4> a("1010");
   std::bitset<4> b("0011");
   std::bitset<4> c("1111");
   a |= b |= c;
   std::cout << a << std::endl; 
   std::cout << b << std::endl;
   return 0;
}

Output

Output of the above code is as follows −

1111
1111