Need quick help - cant find error

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January 13th, 2013, 03:19 PM

sissiv6itleja

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Need quick help - cant find error

HI!

Can somebody find what is wrong with my code. He must multiply negative element of two first rows.

Code:

#include <stdio.h>
 
int main() {

        int A[6][9];
        int i=0;
        int j;
        int number;
       
        /* inserting rows and columns */
       
        while ( i < 6 )
        {
                j=0;
                while ( j < 9)
                {
                        printf("insert array[%d][%d]: ", i, j);
                        scanf("%d", &A[i][j]);
                        j++;
                }
                i++;
        }       
        /*Calculation*/
        arv = 0;
        while ( i < 2 )
        {
                j=0;
                while ( j < 9 )
                {
                        if(A[i][j]<0)
                        {
                        			if (arv==0)
							{
                        	        	         number += A[i][j];
							}
						else
                               number *= A[i][j];       
                        }
                        j++;
                }
                i++;
        }
        printf("two first row negative element multiplyng result is %d\n", number);
        printf("For exit press enter");
        getchar();
        return 0;
}

January 13th, 2013, 03:21 PM

salem

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Have you considered using for loops instead of while loops?

The notation is much more compact, and you might realise that you're not re-initialising a loop variable back to 0 before you start another loop.

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January 13th, 2013, 03:24 PM

sissiv6itleja

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Quote:

Originally Posted by salem

Our professor wants it so that we use the while loop, dont ask me why

January 13th, 2013, 03:31 PM

salem

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So did you figure it out?

> Our professor wants it so that we use the while loop
Well you could write it as a for loop first, just so you know it works, then manually turn it into a while loop.

January 13th, 2013, 03:39 PM

sissiv6itleja

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no i coult not figure it out

By the way sorry for the estonian words in code now its fully in english.

Code:

#include <stdio.h>
 
int main() {

        int A[6][9];
        int i=0;
        int j;
        int number;
       
        /* inserting rows and columns */
       
        while ( i < 6 )
        {
                j=0;
                while ( j < 9)
                {
                        printf("insert array[%d][%d]: ", i, j);
                        scanf("%d", &A[i][j]);
                        j++;
                }
                i++;
        }       
        /*Calculation*/
        number = 0;
        while ( i < 2 )
        {
                j=0;
                while ( j < 9 )
                {
                        if(A[i][j]<0)
                        {
                        			if (number==0)
									{
                        	        	number += A[i][j];
									}
						else
                               number *= A[i][j];       
                        }
                        j++;
                }
                i++;
        }
        printf("two first row negative element multiplyng %d\n", number);
        printf("For exit press enter");
        getchar();
        return 0;
}

January 13th, 2013, 03:42 PM

salem

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Join Date: Jun 2005

Posts: 3,831

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So what's the value of i at the start of the 2nd while loop?

Have you used a debugger to step through the code?

Did you not notice that the 2nd while loop never got executed, because i was still 6 from the exit of the first while loop?

January 13th, 2013, 04:01 PM

sissiv6itleja

Registered User

Join Date: Jan 2013

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It can not be true, it works now ,many many thanks.

Im learning computer systems and i am on the first course, and our programming tacher is not very good so i dont now yet how the debugger works but i will read then about this. And as you see my english is also not very good so please try to explayne easyer.
About the problem - I thought that the first i declarering is enough, that it is main but not locale but it wasnt so.

I have one more task to do today, because its the last day make it. i very hope that you will help me there also.

Need quick help - cant find error

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