Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Yes, short-circuiting and evaluation order are required for operators <code>||</code> and <code>&amp;&amp;</code> in both C and C++ standards.</p> <p>C++ standard says (there should be an equivalent clause in the C standard):</p> <blockquote> <p><strong>1.9.18</strong></p> <p><em>In the evaluation of the following expressions</em></p> <pre><code>a &amp;&amp; b a || b a ? b : c a , b </code></pre> <p><em>using the built-in meaning of the operators in these expressions, <strong>there is a sequence point after the evaluation of the first expression</strong> (12).</em></p> </blockquote> <p>In C++ there is an extra trap: short-circuiting does <strong>NOT</strong> apply to types that overload operators <code>||</code> and <code>&amp;&amp;</code>.</p> <blockquote> <p><em>Footnote 12: The operators indicated in this paragraph are the built-in operators, as described in clause 5. When one of these operators is overloaded (clause 13) in a valid context, thus designating a user-defined operator function, the expression designates a function invocation, and the operands form an argument list, <strong>without an implied sequence point between them.</em></strong></p> </blockquote> <p>It is usually not recommended to overload these operators in C++ unless you have a very specific requirement. You can do it, but it may break expected behaviour in other people's code, especially if these operators are used indirectly via instantiating templates with the type overloading these operators.</p>
    singulars
    1. This table or related slice is empty.
    1. POIs short-circuiting logical operators mandated? And evaluation order?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USAlex B
    1. USAlex B
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POIs short-circuiting logical operators mandated? And evaluation order?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. CODidn't know short-circuiting wouldn't apply to overloaded logic ops, that's intesting. Can you please add a reference to the standard, or a source? I'm not distrusting you, just want to learn more about this.
      singulars
      1. PO
      1. USJoe Pineda
    2. COyeah, that's logical. it's acting as arguments to operator&&(a, b) . it's the implementation of it that says what happens.
      singulars
      1. PO
      1. USJohannes Schaub - litb
    3. COlitb: It's just not possible to pass b to operator&&(a,b) without evaluating it. And there's no way undo evaluating b because the compiler cannot guarantee there aren't side effects.
      singulars
      1. PO
      1. USjmucchiello
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload