I know that I am close, but it wont work. HELP!!!!
void PrintA( int * , int);
void main()
{
int num[3][5] = {
{1, 2,3,4,5},
{6,7,8,9,10},
{11,12,13,14,15},
};
int *num_ptr;
num_ptr = &num[0][0];
PrintA( num_ptr, 5 );
}
void PrintA( int *a, int cols )
{
for (int r = 0; r < 3 ; r++)
{for ( int c = 0; c < 5; c++ )
cout << *(*(a + r) + c) << " ";
cout << endl;
}
} 4 2382
"Super KHB" <lo**@message.end> wrote in message news:Jx0gd.49083 void PrintA( int *a, int cols ) { for (int r = 0; r < 3 ; r++) {for ( int c = 0; c < 5; c++ ) cout << *(*(a + r) + c) << " "; cout << endl; } }
Should the line
cout << *(*(a + r) + c) << " ";
be
cout << *(*(a + 5*r) + c) << " ";
Also, instead of the hardcoded constant "5", do you mean to use the variable
"cols"?
Super KHB wrote: I know that I am close, but it wont work. HELP!!!!
void PrintA( int * , int);
void main() {
int num[3][5] = { {1, 2,3,4,5}, {6,7,8,9,10}, {11,12,13,14,15}, };
Here you have a memory layout looking like this:
num
+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
and the compiler keeps track of calulating the correct offset from the beginning
when given 2 indices
int *num_ptr; num_ptr = &num[0][0];
PrintA( num_ptr, 5 ); }
void PrintA( int *a, int cols ) { for (int r = 0; r < 3 ; r++) {for ( int c = 0; c < 5; c++ ) cout << *(*(a + r) + c) << " ";
Here you assume a memory layout like this:
num
+------+ +----+----+----+----+----+
| o--------->| 1 | 2 | 3 | 4 | 5 |
| | +----+----+----+----+----+
+------+ +----+----+----+----+----+
| o------------------>| 6 | 7 | 8 | 9 | 10 |
| | +----+----+----+----+----+
+------+ +----+----+----+----+----+
| o------------>| 11 | 12 | 13 | 14 | 15 |
| | +----+----+----+----+----+
+------+
( an array of pointers, where each pointer points to an array of int )
Totally different.
--
Karl Heinz Buchegger kb******@gascad.at
> cout << *(*(a + r) + c) << " ";
try this cout << *(a+((cols * r) + c))<< " ";
"Siemel Naran" <Si*********@REMOVE.att.net> wrote: "Super KHB" <lo**@message.end> wrote:
void PrintA( int *a, int cols ) { for (int r = 0; r < 3 ; r++) {for ( int c = 0; c < 5; c++ ) cout << *(*(a + r) + c) << " "; cout << endl; } }
Should the line cout << *(*(a + r) + c) << " "; be cout << *(*(a + 5*r) + c) << " ";
We are dealing with a pointer to int so there should be
exactly one indirection. I would write it as:
a[r * cols + c]
(NB. Actually I wouldn't write this because I think
it is UB. However we have just had a big discussion
with no conclusion on that topic in another thread
so I don't want to start it up again here). This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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