The `|` (bitwise inclusive OR) operator compares the values
(in binary format) of each operand and yields a value whose bit pattern shows
which bits in either of the operands has the value `1`. If both of
the bits are `0`, the result of that bit is `0`; otherwise,
the result is `1`.

Both operands must have an integral or enumeration type. The usual arithmetic conversions on each operand are performed. The result has the same type as the converted operands and is not an lvalue.

Because the bitwise inclusive OR operator has both associative and commutative
properties, the compiler can rearrange the operands in an expression that
contains more than one bitwise inclusive OR operator. Note that the `|` character can be represented by the trigraph `??!`.

The following example shows the values of `a`, `b`, and
the result of `a | b` represented as 16-bit binary numbers:

bit pattern of a |
0000000001011100 |

bit pattern of b |
0000000000101110 |

bit pattern of a | b |
0000000001111110 |

Note:

The bitwise OR (`|`) should not be confused
with the logical OR (`||`) operator. For example,
`1 | 4` evaluates to 5

while

`1 || 4` evaluates to true

while

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