Thread: Help with array tutorials

@Salem: Ok I tried it with out the braces and it does work, that was pretty cool since I thought it would only follow statements within braces but now I know that it does follow for the next statement.
@PehJota: That was very good example and also helped me understand better the loops!

This "concept" actually helped me understand a bit whats going on "pseudocode-wise", from what I understood of the loop:

-X starts at 0 and will loop until x < 8 increasing by 1 each loop.

-Each loop of x contains a loop of Y which starts at 0 and will loop until y < 8 increasing by 1 each loop while maintaining x in current loop.

-Then when the statements within for loop x are complete (the whole loop of y 1-8) it will continue to the next digit, which will cause y to loop again and so on.

which is why it ends like (0 1) (0 2) etc.

Ok that is one thing I didn't get (correct me if I'm wrong).

That answered my second question.


The first one was why is the two seperate for loops, i guess as PehJota says nesting. For example I tried writing:

1.

Code:

 
    #include <iostream>

using namespace std;

int main()
{
  int x;
  int y;
  int array[8][8];

  cout<<"Array Indices:\n";
  for ( x = 0; x < 8;x++ ){
    for ( y = 0; y < 8; y++ )
    return array[x][y] = x * y;//I have even tried with out return and simply like
                               //array[x][y] = x * y;
      cout<<"["<<x<<"]["<<y<<"]="<< array[x][y] <<" ";
    cout<<"\n";
     
}

and 2.

Code:

 #include <iostream>

using namespace std;

int main()
{
  int x;
  int y;
  int array[8][8];
      array[x][y] = x * y;
  cout<<"Array Indices:\n";
  for ( x = 0; x < 8;x++ ) {
    for ( y = 0; y < 8; y++ )
      cout<<"["<<x<<"]["<<y<<"]="<< array[x][y] <<" ";
    cout<<"\n";
  }
  cin.get();
}

This last one makes the program crash which made me laugh :P, but the first question mainly was why do we have to put twice the for x loop, for y loop ? (first right after setting the variables and the array and the after the cout)?

Thanks alot for the previous answers and to the future ones !

Originally Posted by xD!

First I don't get why the for loop is being declared twice.

A multidimensional array is really just a conceptual way of viewing an array. Your array[8][8] is really the same as array[64]. But since your using it as [8][8] the (2) for() loops are used to fill each seperate dimension. Add in a cout to view any random element in the array to see what I am saying, such as array[50].

And if this isn't a help forum for newbies like me I would appreciate a link to a forum where I can get help!

Sometimes the only help you may get is from other newbies!

Beware the critics... They pounce.

Originally Posted by Incantrix

A multidimensional array is really just a conceptual way of viewing an array. Your array[8][8] is really the same as array[64]. But since your using it as [8][8] the (2) for() loops are used to fill each seperate dimension. Add in a cout to view any random element in the array to see what I am saying, such as array[50].




Sometimes the only help you may get is from other newbies!

Beware the critics... They pounce.

Thx for the answer ! I thought that being multidimensional using for loop for x and then for y would be enough but the it declares it again so if I wrote array[8][8][8] would i have to do something like :

for x
for y
for z
then the array x*z*y

and three times more ?

for x
for y
for z

for x
for y
for z

then cout<< etc ?

Hmm, i just feel theres something I'm not understanding exactly.

Tutorials are not exhaustive sources of information. They will not explain every possible use of arrays. As long as you understand the data structure and how to process an array, access individual elements, then you can literally master arrays.

The tutorial does two things: fills a two-dimensional array, and then print the elements and their subscripts. You will not need to do that for every array. This use for arrays is very contrived.

Code:

int i, j;
for( i = 0; i < 8; i++)
   for( j = 0; j < 8; j++)
       cout << "array[" << i << "][" << j << "] = " << i * j << endl;

same output, no array.

So the tutorial just wants you to understand arrays... and there are other sources, such as this one, that would explain in excruciating detail. If you want to know dirty details: read that.

Wow ! Thanks alot for your answers they have helped me alot ! I'll be checkign that website you mentioned white flags, and I can't wait till the books I have ordered arrive.

As for that link it seems to be C and not C++ maybe I would get mixed up due to different syntax or something like that.


Either way thanks alot to those who have helped me !