How to sum two arrays in another array in C?

Question

I want to try to get two arrays and sum them to another array, but it just doens't work, and I don't know why.

My code :

int v1[3],v2[3],v3[3];

for(int i  = 0 ; i < 3; i++) {
    printf("Type a number : \n");
    scanf("%d", &v1[i]);
}

for(int i  = 0 ; i < 3; i++) {
    printf("Type a number : \n");
    scanf("%d", &v2[i]);
}

for(int i  = 0 ; i < 3; i++) {
 v3[i] = v1[i] + v2[i];
 scanf("%d", &v3[i]);

 printf("Total : %d ", &v3[i]);
}

And when I get to type all the 6 numbers, he just don't show Total, and I have to type more to go to exit screen.

Screenshot :

Why do you need a scanf for the result array? ("scanf("%d", &v3[i]);") — AmeyaVS
– AmeyaVS, Commented May 31, 2017 at 3:47
I just wanted to show the result for the user. But as I am new to C, I am newbie to this stuff. — Leandro Mont
– Leandro Mont, Commented May 31, 2017 at 3:50
The final result continue being the same as from the old code, I don't know what is happening. Even if I put the printf out of the for or inside and with the modifications that the answers said, it's the same result. — Leandro Mont
– Leandro Mont, Commented May 31, 2017 at 3:57
Your main problem here is that you either compiled your program with no warnings enabled or that you ignored the warning(s). — August Karlstrom
– August Karlstrom, Commented May 31, 2017 at 4:32

Shuvam · Accepted Answer · 2017-05-31 04:20:38Z

2

What do you exactly want? Summation of each element from two arrays into a new third array? That's it right?

int main(int argc, char** argv) {
    int v1[3],v2[3],v3[3];

    for(int i  = 0 ; i < 3; i++) {
      printf("Type a number for v1 :\t");
      scanf("%d", &v1[i]);

      printf("Type a number for v2 :\t");
      scanf("%d", &v2[i]);
      // Add here
      v3[i] = v1[i] + v2[i]; // Mind you that this could lead to integer overflow.
  }

  printf("\nResult Arr :\n");
  for(int i  = 0 ; i < 3; i++)
    printf("%d\n", v3[i]);
}

answered May 31, 2017 at 4:20

Shuvam

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4 Comments

Leandro Mont Over a year ago

It worked the code, thanks. But as I am new to C, I don't know what that /t means. Could you explain to me, please ?

Leandro Mont Over a year ago

And what this (int argc, char** argv) will do ? Sorry for the newbie question.

Jonathan Leffler Over a year ago

The int main(int argc, char **argv) is the form for the main() function when you use command line arguments. This code doesn't use command line arguments; the main function should be defined using int main(void) to indicate that it is ignoring any command line arguments. The \t (note the backslash, not forward slash /t) is a tab. That's covered in any basic book on C.

Leandro Mont Over a year ago

@JonathanLeffler Thanks for explaning to me, I started to learn C almost 3 months ago, so a lot of things are new to me.

msc · Accepted Answer · 2017-05-31 04:57:37Z

2

What is the purpose of scanf inside the third for loop?

I think remove scanf inside third for loop:

 scanf("%d", &v3[i]);

Also, remove & in printf:

printf("Total : %d ", v3[i]);

Full code: This code working fine on GCC compiler.

#include <stdio.h>

int main()
{
        int v1[3],v2[3],v3[3], i;

        for(i  = 0 ; i < 3; i++)
        {
                printf("Type a number : \n");
                scanf("%d", &v1[i]);
        }

        for(i  = 0 ; i < 3; i++)
        {
                printf("Type a number : \n");
                scanf("%d", &v2[i]);
        }

        for(i  = 0 ; i < 3; i++)
        {
                v3[i] = v1[i] + v2[i];

                printf("Total : %d\n", v3[i]);
        }
}

edited May 31, 2017 at 4:57

answered May 31, 2017 at 3:45

msc

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4 Comments

Leandro Mont Over a year ago

It does not work the same way, because the end result does not have the actual sum of the two vectors.

Jonathan Leffler Over a year ago

@Novatec: your code didn't show that calculation, nor did the question mention it. Changing the rules isn't fair — in extreme cases, the question becomes a 'chameleon question', and they're bad.

Jonathan Leffler Over a year ago

Arguably, the code should check the return value from each of the surviving scanf() calls. But your basic diagnosis is correct.

Leandro Mont Over a year ago

@JonathanLeffler I am sorry for what I did here, your code too works, thanks for helping me. I am new to C, so for me, the third scanf would read the third array and would work, but as it seems, it don't. Again, thanks for the help.

Douglas Daseeco · Accepted Answer · 2017-05-31 03:43:08Z

0

Delete the third scanf and you don't want the ampersand before the v3 in the printf.

answered May 31, 2017 at 3:43

Douglas Daseeco

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1 Comment

Leandro Mont Over a year ago

It does not work the same way, because the end result does not have the actual sum of the two vectors.

Mike · Accepted Answer · 2017-05-31 03:45:03Z

0

First, initialize your array so you won't have a garbage.

`int v1[3] = {0,0,0}, v2[3] = {0,0,0}, v3[3] = {0,0,0};`

in adding both arrays,

for(int i = 0; i < 3; i++){
    v3[i] = v1[i] + v2[i];
    printf("total: %d", v3[i]);
}

answered May 31, 2017 at 3:45

Mike

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Comments

Pras · Accepted Answer · 2017-05-31 03:45:15Z

0

If you want to store result in v3, you need to remove scanf("%d", &v3[i]); from last loop

You need to change

printf("Total : %d ", &v3[i]);//you are passing address here, where printf expects value

to

printf("Total : %d ", v3[i]);

Also you should add a space before %d in each scanf so that it takes care of enter hit from previous input eg

scanf(" %d", &v1[i]);

answered May 31, 2017 at 3:45

Pras

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3 Comments

Leandro Mont Over a year ago

Is still showing Total : 6487568. Even after I removed the scanf, why is that happening ? If I let &v3[i] he just show that, and If I remove, he shows the Total as 2.

Pras Over a year ago

You need to remove & from printf as well

Leandro Mont Over a year ago

It does not work the same way, because the end result does not have the actual sum of the two vectors.

Meet Parekh · Accepted Answer · 2017-05-31 03:47:20Z

0

It is because you added a scanf function in the last for loop which does the summation. So if you just remove that scanf line it will work great. Old code:

int v1[3],v2[3],v3[3]; for(int i = 0 ; i < 3; i++) { printf("Type a  number : \n"); scanf("%d", &v1[i]); } for(int i = 0 ; i < 3; i++) {  printf("Type a number : \n"); scanf("%d", &v2[i]); } for(int i = 0 ; i < 3; i++) { v3[i] = v1[i] + v2[i]; scanf("%d", &v3[i]);    printf("Total : %d ", &v3[i]); }

New code should be

int v1[3],v2[3],v3[3]; for(int i = 0 ; i < 3; i++) { printf("Type a number : \n"); scanf("%d", &v1[i]); } for(int i = 0 ; i < 3; i++) { printf("Type a number : \n"); scanf("%d", &v2[i]); } for(int i = 0 ; i < 3; i++) { v3[i] = v1[i] + v2[i];  printf("Total : %d ", &v3[i]); }

That should do it.

answered May 31, 2017 at 3:47

Meet Parekh

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1 Comment

Leandro Mont Over a year ago

It does not work the same way, because the end result does not have the actual sum of the two vectors.

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