## Re: loops and arrays

• From: "Littlefield, Tyler" <tyler@xxxxxxxxxxxxx>
• To: <programmingblind@xxxxxxxxxxxxx>
• Date: Wed, 17 Oct 2007 13:49:44 -0600

```srand(time(NULL)) is what I've always seen.
Thanks,
Tyler Littlefield.
"My programs don't have bugs, just randomly added features."
msn: tyler@xxxxxxxxxxxxx
email: tyler@xxxxxxxxxxxxx
aim: st8amnd2005
web: tysdomain.com
```
----- Original Message ----- From: "Graham Hardy" <graham.hardy@xxxxxxxxx>
```To: <programmingblind@xxxxxxxxxxxxx>
Sent: Wednesday, October 17, 2007 8:42 AM
Subject: RE: loops and arrays

```
```Hi Daniel - I should point out that the rand () function works on an
algorithm based on a 'seed,' which is basically a number that you assign.
You assign the seed with the function void srand (int seed). If you don't
assign a seed, then it would use the seed of 1, which would end up
```
generating exactly the same sequence of random numbers from one time to the
```next. This is also a good reason for not assigning a constant literal as a
seed either: it will still be the same from one runtime to the next. I
believe one convention is to get the current second, using a function in
```
time.h which I don't have the time to look at just now, and put that as your
```seed. Another convention is that you usually don't want such long random
```
numbers. That is, you probably would want values between, say, 1 and 100, or
```something like that. In this case, you would want to use the modulus
operator, as, x = 1 + (rand () % 100). I hope this is helpful. -Graham.

-----Original Message-----
From: programmingblind-bounce@xxxxxxxxxxxxx
[mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Daniel Dalton
Sent: October 16, 2007 3:19 PM
To: programmingblind@xxxxxxxxxxxxx
Subject: loops and arrays

Hi,

Could someone help me out with this?
I have an array called array declared like this:
int array [5][4];
So I think this is called a multidimensional  array.

The book said I need to assign a random number to each array index.
(Using the rand library function.
In stlib.h)

I then have to print them to the screen.
In a table. From what I can understand 5 column's and 4 rows.
Should my code look something like this? It doesn't seem to work.
Could someone tell me where I am going wrong?

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

int main ()
{
int array[5][4];
int a, b;

for(a =0; a < 5; a++)
{
for(b =0; b < 4; b++)
{
array [a][b] =rand ();
}
}

/*print them */
for(a =0; a <5; a++)
{
for(b =0; b < 4; b++)
{
/* I don't know what to do with this part.*/

```
Can someone help me finish it off? I have know idea how to get them to print
```in the table.
Is there any other problems?

And one more question:
How do loops inside other loops work?
If I wrote:
for(i =0; i <200; i++)
{
for(x =0; x < 10; x++)
{
/*code*/
}
}
```
So would the loop with x (the loop inside the first loop) be executed while
```the first loop is true?
```
So while the first loop is executing would it run the whole second loop for
```one increment of I.
so would the second loop count up to 9 for every increment of i?

Thanks for any help.

--
Daniel Dalton

http://members.iinet.net.au/~ddalton/
daniel.dalton47@xxxxxxxxx
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