How to get size of sub array - not the count of characters member ?

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Here is my array.
Is it correct syntax?
I need to get size of each subarray.
Then I like to retrieve specific subarray.

C++

// test array
   const QStringList list_array[10]
   {
       {   "SubWindow terminal all options         ",
           "SubWindow terminal configure           ",
           "SubWindow terminal setup               ",
           "SubWindow terminal connect  serial     ",
           "SubWindow terminal connect  Bluetooth  ",
           "SubWindow terminal DEBUG / TRACE       ",
           "SubWindow terminal connect  Bluetooth  ",
           "SubWindow terminal DEBUG / TRACE       ",
           "SubWindow terminal LAST member         "
       },
       { "SubsubWindow bluetoothctl help        (QMdiArea )",
           "SubsubWindow bluetoothctl list  (QMdiArea )",
           "SubsubWindow bluetoothctl devices (QMdiArea )",
           "SubsubWindow bluetoothctl show  (QMdiArea )" },
       { "SubWindow terminal     (QMdiArea )",
           "SubWindow hcitool      (QMdiArea )",
           "SubWindow bluetoothctl (QMdiArea )",
           "SubWindow system       (QMdiArea )" },
       { "SubsubWindow bluetoothctl help        (QMdiArea )",
           "SubsubWindow bluetoothctl list  (QMdiArea )",
           "SubsubWindow bluetoothctl devices (QMdiArea )",
           "SubsubWindow bluetoothctl show  (QMdiArea )" },
       { "SubsubWindow hcitool        (QMdiArea )",
           "SubsubWindow hcitool   dev  (QMdiArea )",
           "SubsubWindow hcitool   scan (QMdiArea )",
           "SubsubWindow hcitool   inq  (QMdiArea )",
           "SubWindow system  LAST array member      (QMdiArea )"
       }
   };

My test code

C++

for(int TEST = 0; TEST < 5; TEST++)
 {
     text = " test ARRAY size TEST ";
     text += QString::number (TEST );
     text += " ";
     text += QString::number (list_array[TEST][0].size());
     text += " sizeof ";
     text +=  QString::number (sizeof (list_array[TEST]));

             qDebug() << text;
      }

My test code result

C++

 // test
 " test ARRAY size TEST 0 39 sizeof 8"
" test ARRAY size TEST 1 49 sizeof 8"
" test ARRAY size TEST 2 34 sizeof 8"
" test ARRAY size TEST 3 49 sizeof 8"
" test ARRAY size TEST 4 39 sizeof 8"

With index = 0, the list_array[index].size(); return correct size of main (string) array,

with index = 0 and "sub array = 0 "
the list_array[index][0].size(); returns first member of main array count of characters.

I am after size of the first sub array.

C++

int subSize = list_array[index].size();
                int subsubSize = list_array[index][0].size();

What I have tried:

I did try to vary the index - but that seems silly....( just to satisfy the counter )

Posted 19-Jan-24 13:16pm

Salvatore Terress

Updated 22-Jan-24 16:13pm

v4

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merano99 19-Jan-24 21:49pm

What is the declaration of list_array?

Richard MacCutchan 20-Jan-24 4:42am

That will only work if list_array[index][0] is also a Qt array. If it is something else then you will need to use some other method that can understand the data structure.

3 solutions

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Rick York · Answer 1 · 2024-01-19T14:30:00

Your question is not clear. This code works for me :

C++

const int dimOne   = 8;
const int dimTwo   = 10;
const int dimThree = 12;

typedef int ThreeD[ dimOne ][ dimTwo ][ dimThree ];
ThreeD array;
int sizeTwo = sizeof( array[ 0 ][ 0 ] );
printf( "sizeTwo is %d\n", sizeTwo );

I am not familiar with a class called array that has a size method. What library is it in?

Richard MacCutchan · Answer 2 · 2024-01-22T21:58:00

Solution 2

Why are you using sizeof on a pointer? As you see it correctly tells you that each pointer is 8 bytes long. You need to use a function/method that gives you the length of the actual character string pointed to by list_array[TEST][0].

Posted 22-Jan-24 21:58pm

Richard MacCutchan

Comments

Salvatore Terress 23-Jan-24 10:22am

Unfortunately that is not what I need - I need size , # , of members in subarray.
That is why I asked if my array definition is correct.

for(int TEST = 0; TEST < 5; TEST++)
{
text = " test ARRAY size TEST ";
text += QString::number (TEST );
text += " ";
text += QString::number (list_array[TEST][0].size());
text += " sizeof ";
text += QString::number (sizeof (list_array[TEST][0]));

qDebug() << text;
}

Output of code above:

" test ARRAY size TEST 0 39 sizeof 8"
" test ARRAY size TEST 1 49 sizeof 8"
" test ARRAY size TEST 2 34 sizeof 8"
" test ARRAY size TEST 3 49 sizeof 8"
" test ARRAY size TEST 4 39 sizeof 8"

Richard MacCutchan 23-Jan-24 10:48am

But what you are referring to are not arrays, they are strings. You have a single array of QStringList items. And each list contains a number of strings. So list_array[TEST] refers to one of the lists. And list_array[TEST][0] refers to the first string in that list. See QStringList Class | Qt Core 6.6.1[^] for full details.

Salvatore Terress 23-Jan-24 11:29am

Just update
I have this (working( example of single list I will try to adapt to "two level " list array

// test
QStringList fonts = { "Arial", "Helvetica", "Times" };
for (int i = 0; i < fonts.size(); ++i)
{
cout << fonts.at(i).toLocal8Bit().constData() <

Richard MacCutchan 23-Jan-24 11:57am

I am not sure I understand exactly what you are trying to achieve.

Salvatore Terress · Answer 3 · 2024-01-23T14:22:00

Solution 3

SOLVED

list_array[index].size();

sorry OF forgot the solution he has received few weeks ago

Posted 23-Jan-24 14:22pm