Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>You can pass an array by value, but you have to first wrap it in a struct or class. Or simply use a type like std::vector.</p> <p>I think the decision was for the sake of efficiency. One wouldn't want to do this most of the time. It's the same reasoning as why there are no unsigned doubles. There is no associated CPU instruction, so you have to make what's not efficient very hard to do in a language like C++. </p> <p>As @litb mentioned: "C++1x and boost both have wrapped native arrays into structs providing std::array and boost::array which i would always prefer because it allows passing and returning of arrays within structs"</p> <p>An array is a pointer to the memory that holds that array and the size. Note it is not the exact same as a pointer to the first element of the array.</p> <p>Most people think that you have to pass an array as a pointer and specify the size as a separate parameter, but this is not needed. You can pass a reference to the actual array itself while maintaining it's sizeof() status.</p> <pre><code>//Here you need the size because you have reduced // your array to an int* pointing to the first element. void test1(int *x, int size) { assert(sizeof(x) == 4); } //This function can take in an array of size 10 void test2(int (&amp;x)[10]) { assert(sizeof(x) == 40); } //Same as test2 but by pointer void test3(int (*x)[10]) { assert(sizeof(*x) == 40); //Note to access elements you need to do: (*x)[i] } </code></pre> <p>Some people may say that the size of an array is not known. This is not true. </p> <pre><code>int x[10]; assert(sizeof(x) == 40); </code></pre> <p>But what about allocations on the heap? Allocations on the heap do not return an array. They return a pointer to the first element of an array. So new is not type safe. If you do indeed have an array variable, then you will know the size of what it holds. </p>
    singulars
    1. This table or related slice is empty.
    1. POWhy C or C++ does not allow passing array by values to function
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USBrian R. Bondy
    1. USBrian R. Bondy
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    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. COYou see that [10] in the function parameter? That's where the size is compimg from. The reference has nothing to do with it.
      singulars
      1. PO
      1. This table or related slice is empty.
    2. COit's more type safe than the test1
      singulars
      1. PO
      1. USBrian R. Bondy
    3. CO@Neil Butterworth: The size of an array is part of the array type itself. If you wanted variable size you'd be better off with an std::vector.
      singulars
      1. PO
      1. USBrian R. Bondy
 

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