Which bitwise operator is used to set a particular bit to 1 in a variable?

The bitwise operator used to set a particular bit to 1 in a variable is the OR operator (|). Here are the steps to do it:

1. First, you need to decide which bit position you want to set to 1. Let's say you want to set the nth bit to 1.

2. Create a mask by shifting 1 to the nth position. In most programming languages, this can be done using the left shift operator (<<). For example, in C++, you would do: int mask = 1 << n;

3. Finally, use the bitwise OR operator (|) to set the nth bit of your variable to 1. If your variable is named 'var', you would do: var = var | mask;

This will set the nth bit of 'var' to 1, regardless of what it was before. The reason this works is that the bitwise OR operator sets each bit in the result to 1 if either corresponding bit in the two operands is 1. So, if the nth bit in 'var' is already 1, it stays 1, and if it's 0, it becomes 1.