The sum of differences of array elements from each other-CodePudding

That is my code. But the output is wrong. My expected output is:

input: 1 2 3
output: 3 2 3;
but the actual output is 2 1 0 on my code.

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

int main(void) {
    int n; // create a variables to decide how many number that they want to store on array
    int position[10];
    int sumdiffs[10];
    printf("How many number you want to enter here: ?\n"); // let users enter how much number
    scanf("%d", &n);
    // accept users number
    for (int m = 0; m < n; m  ) {
        printf("Please enter number %d:", m   1);
        scanf("%d", &position[m]);
    }

    for (int i = 0; i < n; i  ) {
        for (int j = 0; j < n; j  ) {
            sumdiffs[i] = abs(position[i] - position[j]);
        } 

        printf("%d\n", sumdiffs[i]);
    }

    return 0;
}

That is my test.

How many number you want to enter here: ?
3
Please enter number 1:1
Please enter number 2:2
Please enter number 3:3
2
1
0

CodePudding user response：

You are not computing the sum of differences, you only store each difference so the array sumdiffs contains the last difference.

Note also that your code has undefined behavior for n greater than 10 because you access the arrays beyond their boundaries.

Here is a modified version:

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

int main(void) {
    int n;
    printf("How many numbers you want to enter here?\n");
    if (scanf("%d", &n) != 1 || n <= 0)
        return 1;
    // arrays defined with the correct size (hopefully not too large)
    int position[n];
    int sumdiffs[n];
    // read the numbers from the user
    for (int m = 0; m < n; m  ) {
        printf("Please enter number %d: ", m   1);
        if (scanf("%d", &position[m]) != 1)
            return 1;
    }

    for (int i = 0; i < n; i  ) {
        sumdiffs[i] = 0;
        for (int j = 0; j < n; j  ) {
            sumdiffs[i]  = abs(position[i] - position[j]);
        } 
        printf("%d\n", sumdiffs[i]);
    }
    return 0;
}

CodePudding user response：

First, clear the accumulated sums:

for (int i = 0; i < n; i  ) {
    sumdiffs[i] = 0;

Then, just change

sumdiffs[i] = abs(position[i] - position[j]);

into

sumdiffs[i]  = abs(position[i] - position[j]);

to accumulate the differences.