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copied!<p><strong>Updated Answer</strong> - my original was misleading and incomplete.</p> <p>First I should apologize for much of my comments and responses to this question.</p> <p>After reading the spec, the distinction between bitwise and conditional operators is much less clear cut.</p> <p>According to section <a href="http://www.jaggersoft.com/csharp_standard/14.10.htm" rel="noreferrer">14.10 of ECMA-334</a>:</p> <blockquote> <p>The &, ^, and | operators are called the logical operators.</p> </blockquote> <p>for integer operations:</p> <blockquote> <p>1 The & operator computes the bitwise logical AND of the two operands, the | operator computes the bitwise logical OR of the two operands, and the ^ operator computes the bitwise logical exclusive OR of the two operands. 2 No overflows are possible from these operations.</p> </blockquote> <p>According to section <a href="http://www.jaggersoft.com/csharp_standard/14.11.htm" rel="noreferrer">14.11:</a></p> <blockquote> <p>The && and || operators are called the conditional logical operators. 2 They are also called the "short-circuiting" logical operators.</p> </blockquote> <p>14.11.1</p> <blockquote> <p>1 When the operands of && or || are of type bool, or when the operands are of types that do not define an applicable operator & or operator |, but do define implicit conversions to bool, the operation is processed as follows: 2 The operation x && y is evaluated as x ? y : false. 3 In other words, x is first evaluated and converted to type bool. 4 Then, if x is true, y is evaluated and converted to type bool, and this becomes the result of the operation. 5 Otherwise, the result of the operation is false. 6 The operation x || y is evaluated as x ? true : y. 7 In other words, x is first evaluated and converted to type bool. 8 Then, if x is true, the result of the operation is true. 9 Otherwise, y is evaluated and converted to type bool, and this becomes the result of the operation.</p> </blockquote> <p>14.11.2</p> <blockquote> <p>1 When the operands of && or || are of types that declare an applicable user-defined operator & or operator |, both of the following must be true, where T is the type in which the selected operator is declared: 2 The return type and the type of each parameter of the selected operator must be T. 3 In other words, the operator must compute the logical AND or the logical OR of two operands of type T, and must return a result of type T. 4 T must contain declarations of operator true and operator false. Paragraph 2 1 A compile-time error occurs if either of these requirements is not satisfied. 2 Otherwise, the && or || operation is evaluated by combining the user-defined operator true or operator false with the selected user-defined operator: 3 The operation x && y is evaluated as T.false(x) ? x : T.&(x, y), where T.false(x) is an invocation of the operator false declared in T, and T.&(x, y) is an invocation of the selected operator &. 4 In other words, x is first evaluated and operator false is invoked on the result to determine if x is definitely false. 5 Then, if x is definitely false, the result of the operation is the value previously computed for x. 6 Otherwise, y is evaluated, and the selected operator & is invoked on the value previously computed for x and the value computed for y to produce the result of the operation. 7 The operation x || y is evaluated as T.true(x) ? x : T.|(x, y), where T.true(x) is an invocation of the operator true declared in T, and T.|(x, y) is an invocation of the selected operator |. 8 In other words, x is first evaluated and operator true is invoked on the result to determine if x is definitely true. 9 Then, if x is definitely true, the result of the operation is the value previously computed for x. 10 Otherwise, y is evaluated, and the selected operator | is invoked on the value previously computed for x and the value computed for y to produce the result of the operation. Paragraph 3 1 In either of these operations, the expression given by x is only evaluated once, and the expression given by y is either not evaluated or evaluated exactly once. Paragraph 4 1 For an example of a type that implements operator true and operator false, see §18.4.2.</p> </blockquote>

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