Databases
StackOverflow2013
Postsdbo
POWhy not non-const reference to temporary objects?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POWhy not non-const reference to temporary objects?
    primarykey
    data
    text
    <p>C++ allows assignment of temporary objects only to const reference. It wont allow assignement of temporary objects to reference.</p> <p>For example: </p> <pre><code>String&amp; a = String("test"); // Error const String&amp; a = String("test"); // Ok </code></pre> <p>Everywhere I google for this result, i only see the following answers</p> <ol> <li>Modifying temporary objects would cause unidentifiable problems</li> <li>Modifying temporary objects is dangerous</li> <li>At some point of time, you will forget it is a temporary variable</li> </ol> <p>It's been said, temporary objects vanishes after the statement. So you should not modify it.</p> <p>If C++, is so keen in blocking modifying the temporary objects, it should have blocked reading the temporary objects right? If the temporary object is vanished, then there is no point in reading contents from there right? The possible cases, where a right can occur, could also involve the read too.</p> <p>Then why its been blocking write alone and allowing read? </p> <p>Please give me a solid c++ code explanation.</p> <p>Please dont deviate the question by pointing some alternatives. Please give me solid answer with code why const int &amp; is allowed and int &amp; is not allowed for temporary objects.</p> <p>One says &amp;&amp; is there.. My question different.. ANother say,changing will not reflect.. Changing will not reflect even when it is const int &amp; too. Eg: double a; Const int &amp; i = a; a++; will not affect i..</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USuser738471
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTDuplicate
    3. PL
      singulars
      1. LTLinked
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POWhy not non-const reference to temporary objects?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POWhy not non-const reference to temporary objects?
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    3. VO
      singulars
      1. POWhy not non-const reference to temporary objects?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI'm not sure I understand the question. Does [this](http://stacked-crooked.com/view?id=49e766dcb26e7f773e3b497c2ff41a52) count as reading from a temporary? If you're talking about one that's passed to a function, you need to copy it, move it, or use a const reference, which extends its life.
      singulars
      1. POWhy not non-const reference to temporary objects?
      1. USchris
    2. CO+1 I've wondered about this too.
      singulars
      1. POWhy not non-const reference to temporary objects?
      1. USMehrdad
    3. COI think it's very hard to analyze all the references to an object for compiler writers to give any warranties.
      singulars
      1. POWhy not non-const reference to temporary objects?
      1. USDmytro Sirenko
 

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