asked on

can someone help me with this logic

im still quite new in writting C so this might be a silly question

what im trying to do is:

have 2 arrays for example

a[]={0,1,2,3}

and

b[][]={{0,2,1,3},
{2,0,5,8},
{1,5,0,7},
{3,8,7,0}}

and based on the numbers from array a[] use them as the locations for numbers in array b
by taking pairs from the first array

so here we have a[]'s first 2 numbers 0 and 1

then the number from b[][] = 2

the second pair from a[] is 1 and 2

then b[][]=5 and so on

any ideas how should i do that?

ultimately i want to find the sum based on the sequence i gave it in a[]
but i think i know how to do that bit

thanks :)

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ozo

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Kent Olsen

Hi Goofy,

You'll probably want a little different structure for b[][] as to C, it's nothing more than a memory region. You're probably thinking that b[][] is a two-dimensional array like b[4][4]. But since the size isn't declared, C can't index into your array.

There are a couple of ways around this. One is to define b[][] as a fixed size array, such as b[4][4]. The other is to define *b* as an array of pointers such as **b or *b[]. You'd then use malloc() to assign memory to each row of data. C will figure that out and let you index into it, but setting it up as constant/static memory (initialized by the compiler) is challenging.

Kent

goofy26

ASKER

oh yes, b's size would be fixed sorry i forgot to mention that...

i will try ur suggestion ozo thanks :)

goofy26

ASKER

thanks this is what i couldnt think of :)

i made it do the sum as well :)

thanks a lot to both

#include "stdafx.h"
#include <stdio.h>
 
int _tmain(int argc, _TCHAR* argv[])
{
 
	int a[4]={0,1,2,3};
	int sum=0;
 
	int i;
 
	int k[4][4]={{ 0,12,10,11},
				{12, 0, 5, 8},
				{10, 5, 0, 7},
				{11, 8, 7, 0}};
 
	for(i=0;i<3;i++){
		
		
		printf("Numbers are: %d\n",k[a[i]][a[i+1]]);
		sum+=k[a[i]][a[i+1]];
		}
	printf("sum is: %d\n",sum);
 
	return 0;
}

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