how to scan an int dinamic 2d array..

i dont know when each row ends

its not a string
that i could say stop when you see \0

can i find the length of row 0 by

sizeof(arr[0])/sizeof(int)


??

>> can i find the length of row 0 by

Not if it's a dynamically allocated array. In that case, you'll just need to store the size somewhere.

how to find the length of a column 0
this is for row

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


void main()
{
        int arr[10][10]={0};
        int t=sizeof(arr[0])/sizeof(int);
        printf("%d",t);
}

---

Quote:

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can i find the length of row 0 by

sizeof(arr[0])/sizeof(int)

---

That only works if your array is declared with a static size like:

Code:

---

int a[5][5];

---

It will not work if you have used pointers to dynamically allocate the size of the rows.

EDIT: I guess I should have refreshed the page before posting, Sebastiani beat me to it.

The column is

Code:

---

sizeof(arr) / (t * sizeof(arr[0][0]);

---

As stated above, this doesn't at all work for dynamic arrays, since the sizeof only works for variables that are known size at the time of compilation. Dynamic arrays are specifically used when you do NOT know the size at time of compilation.

--
Mats

ahh so how to do this with dinamic allocation
??

(suppose i am not given the size and i need to find it)

It also doesn't work if you're passing the array to a function.


Quzah.

>> how to find the length of a column 0

Hint: if sizeof(arr[0]) gives you the size of a single row and sizeof(a) gives you the size of the entire data structure, then the column length would be the result of some arithmetic operation between the two.

>> ahh so how to do this with dinamic allocation

Wasn't that already answered?

no it havent been
it just been said that my method doesnt work on dinamic array

Quote:

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Originally Posted by transgalactic2

ahh so how to do this with dinamic allocation
??

(suppose i am not given the size and i need to find it)

---

You CAN NOT find the size of a dynamic allocation in any generic/portable/reliable way. Of course, you can have markers to mark the end, but that's not generic, because some particular value (such as zero, -1, -32768 or some other value) is then "invalid" for the normal array values.

So, no, you can't do that.

--
Mats

Here is how to do it for dynamic arrays:

Code:

---

int** a;
a = malloc(COLUMN_SIZE * sizeof(int*));
for(i = 0; i < COLUMN_SIZE; i++)
    a[i] = malloc(ROW_SIZE * sizeof(int));

printf("column size is: %d\n", COLUMN_SIZE);
printf("row size is: %d\n", ROW_SIZE);

---

See what I did there?

i need to find some number in a cell of dinamic 2d array

how to do that
if i dont know where ends each row
and how many row are there
?

Quote:

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Originally Posted by transgalactic2

i need to find some number in a cell of dinamic 2d array

how to do that
if i dont know where ends each row
and how many row are there
?

---

Now you're just trolling us... right?

>> no it havent been.
>> it just been said that my method doesnt work on dinamic array

Quote:

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Originally Posted by Sebastiani

>> can i find the length of row 0 by

Not if it's a dynamically allocated array. In that case, you'll just need to store the size somewhere.

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