How do I create a function to change values in an array?

Question

Write a function int set_array(int *v, int i, int j, int k) that sets the elements i to j to a specific value k among the elements of the int array v of size n (<= 100). This is the given problem.

When I input 10 0 9 -1, to set all the elements it comes out normally as -1.

However, when 5 2 2 0 is input, to set only element [2], all output values come out as 0.

I am using eclipse and no error came out. Which part is wrong?

#include <stdio.h>

int set_array(int* v, int i, int j, int k)
{
    int t;
    for (t = i; t <= j; t++)
    {
        v[t] = k;
    }
    return 0;
}

int main()
{
    int t;
    int size, value;
    int start, end;

    scanf("%d %d %d %d", &size, &start, &end, &value);

    int array[size];

    for (t = 0; t < size; t++)
    {
        scanf("%d", &array[t]);
    }

    set_array(array, start, end, value);

    for (t = 0; t < size; t++)
    {
        printf("%d\n", array[t]);
    }

    return 0;
}

Aside: you know what int n, i, j, k, t; are for, but we don't. Code is easier to follow when meaningful identifier names are used. — Weather Vane
– Weather Vane, Commented Nov 26, 2020 at 14:25
It is not wrong. You did not explicitly set elements [0], [1], [3] and [4], and they happened to be 0. — Weather Vane
– Weather Vane, Commented Nov 26, 2020 at 14:31
Now that the typos are fixed, I cannot reproduce the problem. So, the close reason is still valid. — user3657941
– user3657941, Commented Nov 26, 2020 at 14:50

ACoelho · Accepted Answer · 2020-11-26 18:28:00Z

2

The initialization of the array is incorrect. In scanf and printf the i should be replaced by the letter t.

edited Nov 26, 2020 at 18:28

ACoelho

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answered Nov 26, 2020 at 14:47

Sadra

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Comments

ACoelho · Accepted Answer · 2020-11-26 14:29:25Z

1

You are mixing t and i as the for loops indexes:

for (t = 0; t < n; t++)
{
    scanf("%d", &ary[i]);
}

In this case you only scan i position, not the t running the for loop Be careful using many one letters variables...

answered Nov 26, 2020 at 14:29

ACoelho

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4 Comments

ACoelho Over a year ago

I guess it needs clarification

Seungjea lee Over a year ago

I'm not sure why it's 0. I entered 5 2 2 0 and 1 2 3 4 5 and they all changed to 0. And which ones weren't scanned?

ACoelho Over a year ago

A uninitiated array has undefined behavior (sorta), if you try and read it before any value is added it can show any value, in your case a bunch of zeroes. change your scan loop to for (t = 0; t < n; t++){scanf("%d", &ary[t]);} and you'll read the t'th element on every iteration

Weather Vane Over a year ago

I missed the original typo.

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