Thread: Help! Programming Problem

You can define a 2D array like this:

Code:

int two_d[3][3] = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9}
};

That was defining and intitializing an array at the same time. If you don't need to initialize it by hand, or have some other way of doing it, then you can simply do:

Code:

sometype arrayname[ somesize1 ][ somesize2 ] = {0}; //initialize all to zero

Then, say you want to initialize them so each one has an incremented number...

Code:

z = 0;
for( y = 0; y < somesize1; y++ )
    for( x = 0; x < somesize2; x++ )
        arrayname[ y ][ x ] = z++;

It just depends on what you want to stick in each array, and if you care if they're initialized to specific values that are easier to type them by hand at the beginning, or to have a formulae do it, or what not.


Quzah.

Isn't it supposed to exit with code 0?

I think it has to do with how you pass the array as a parameter to findMax().

Code:

#include <stdio.h>

int findmax(int (*array)[3]);

int main(void) {
    int nums[3][3] = {
        {2, 4, 3},
        {9, 5, 6},
        {7, 4, 5}
    };

    printf("Max: %i\n", findmax(nums));
    return 0;
}

int findmax(int (*array)[3]) {
    int x, y, max = 0;
    for(x = 0; x < 3; x ++) {
        for(y = 0; y < 3; y ++) {
            if(array[x][y] > max) max = array[x][y];
        }
    }

    return max;
}

Code:

printf("The maximum value is %d ", findMax(*nums, 200));
return 0;
}
int findMax(int vals[], int numEls) /*find the maximum value*/
{
    int i, *nums, max = vals [0];
    for (i=1; i < 3; ++i, ++ vals);

What's your fascination with the number 200? Did you just pull this out of your ass or what? No. 200 = bad. Try actually passing the size of the row instead of some made up number.

Next, why aren't you using numEls? You pass it, even if it's wrong, but you don't do anything with it. Don't you pay attention to your compiler's messages? You should be doing:

Code:

    for (i=0; i < numEls; ++i, ++ vals)

Furthermore, you still keep putting ; at the end of your loops. Stop. Also, arrays start at zero not one.

Code:

    for (i=1; i < 3; ++i, ++ vals);

Also, your function takes a single dimension array, but you're trying to force feed it a multi-dimension array. That's wrong too. If you did want to use your two dee array, you'd do this:

Code:

findMax( nums[ NUMBEROFTHEROWYOUWANTTOPASS ], LENGTHOFTHEROWYOUAREPASSING )

Such as:

Code:

findMax( nums[ 0 ], 3 )

If you're just passing a single dimension array, you can simply do:

Code:

function( int foo[], size_t s ) { ... }

int array[ 5 ];

function( array, 5 );

Like so.

Quzah.

dwks,
Thanks! I don't know what the result should be with a 2d array.
I only have and example with a simple array and that does give me the maximum number.
I will try this.

quzah, Well.... Sorry that I seem to be getting you upset, but you don't have to be so impolite with me. I am trying to learn and do make mistakes. the 200 is one I forgot to correct. Learning C Programming just with a book isn't the easiest for everyone. So I 'm doing my best. I do want to understand what are the mistakes I make, so thank you.
I've learned something about the findMax function.

Also, your function takes a single dimension array, but you're trying to force feed it a multi-dimension array. That's wrong too. If you did want to use your two dee array, you'd do this:

So if I want it to find the maximum value out of all the rows, can I do that??

I'll try everything you guys have said and let you know.

Originally Posted by flicka

quzah, Well.... Sorry that I seem to be getting you upset, but you don't have to be so impolite with me. I am trying to learn and do make mistakes. the 200 is one I forgot to correct. Learning C Programming just with a book isn't the easiest for everyone. So I 'm doing my best. I do want to understand what are the mistakes I make, so thank you.
I've learned something about the findMax function.
So if I want it to find the maximum value out of all the rows, can I do that??

I'll try everything you guys have said and let you know.

Nah. I don't usually get upset, long term anyway. That's just how I am. I knew where the 200 came from. I was trying to get you to think about what you're actually putting down. It's hard to fix a problem if you don't pay attention to what you're doing.

You just go through each row and each colum. Your pair of loops you started with had the right idea. You just need to make sure you have the right number for each counter's max, and that you don't have a ; on the end of them.


Quzah.

Code:

*(vals + i)

is the same as

Code:

vals[i]

and

Code:

*vals

is the same as

Code:

vals[0]

Oh, and you don't need m. Just use i*20+j.