Code Bug: Segmentation Fault [EVERYTIME] - c

Question

I am writing this C/C++ program that is suppose to find the mean, median, and mode of a varied size array. Although, I keep getting a Segmentation Fault regardless of the input. What is wrong with my code? Any suggestions always appreciated! :)
Here is the code:
#include <stdio.h>
//#include <string.h>
//#include <math.h>
#include <stdlib.h>
Prototypes:
void sort(double*[],int);
static int min(double,double[],int);
double mean(double[],int);
double median(double[],int);
double mode(double[],int);
int numberOf(double,double[],int);
Main Function:
int main() {
int i;
scanf(" %d ",&i); //10
double arr[i]; //array that contains all the values and will be sortted
for (int j=0; j<i; j++) { //64630 11735 14216 99233 14470 4978 73429 38120 51135 67060
scanf(" %lf ",&arr[j]);
}
printf("%.1lf\n%.1lf\n%.0lf",mean(arr,i),median(arr,i),mode(arr,i));
return 0;
}
Sort Function:
The end result should update the array arr from the call in the Median Function. Changes the used values in the original array to -1 until that is the entire array.
void sort(double* arr[],int l) {
double arr2[l];
for (int i=0; i<l; i++) {
int j;
if (i)
j = min(arr2[i-1], *arr, l);
else
j = min(0, *arr, l);
arr2[i] = *arr[j];
*arr[j] = -1;
}
for (int i=0; i<l; i++) {
*arr[i] = arr2[i];
}
}
Min Function (helper function for the Sort Function):
Finds the minimum value amongst the array elements that is greater than or equal to minLookingTo
Returns the position the value is in.
static int min(double minLookingTo,double arr[],int l) {
int minP;
double minA = minLookingTo;
for (int i=0; i<l; i++) {
if (arr[i] == -1)
continue;
if (minLookingTo<=arr[i] && arr[i]<=minA) {
minP = i;
minA = arr[i];
}
}
return minP;
}
Mean Function:
Returns the mean of the inputted array with the length l
double mean(double arr[],int l){
double total = 0;
for (int i=0; i<l; i++) {
total += arr[i];
}
return total/l;
}
Median Function:
Uses the Sort Function. Assuming that works, returns the median.
double median(double arr[],int l){
sort(&arr,l);
double d = arr[(l/2)+1];
double dd = arr[(l/2)];
if (l%2!=0)
return d;
return (d+dd)/2;
}
Mode Function:
Uses the NumberOf Function to determine the array element with the maximum amount of repeats. Returns the lowest value of the highest (equal) repeats.
double mode(double arr[],int l){
int maxA;
int maxP;
for (int i=0;i<l;i++) {
int j = numberOf(arr[i],arr,l);
if (j>maxA) {
maxA = j;
maxP = i;
}
else if (j==maxA && arr[maxP]>arr[i])
maxP = i;
}
double d = arr[maxP];
return d;
}
NumberOf Function:
Helper function for the Mode Function. Returns the amount of elements with the looking value.
int numberOf(double looking,double arr[],int l) {
int amount = 0;
for (int i=0; i<l; i++)
if (looking == arr[i])
amount++;
return amount;
}

Answer 1

I tracked your segmentation fault to your sort() routine called by median(). Rather than fix sort(), I substituted qsort() from the library to convince myself that's the problem:
// Median Function:
// Uses the Sort Function. Assuming that works, returns the median.
int comparator(const void *p, const void *q) {
double a = *((double *) p);
double b = *((double *) q);
return (a > b) - (a < b); // compare idiom
}
double median(double array[], int length) {
// sort(array, length);
qsort(array, length, sizeof(double), &comparator);
double d = array[length / 2];
if (length % 2 != 0) {
return d;
}
double dd = array[(length / 2) - 1];
return (d + dd) / 2;
}
For the example list of numbers provided, after correcting the rest of the code, this returns a median of 44627.5
Other fixes:
You're missing a final newline here:
printf("%.1lf\n%.1lf\n%.0lf",mean(arr,i),median(arr,i),mode(arr,i));
You should probably initialize the variables in mode():
double mode(double array[], int length) {
int maxA = INT_MIN;
int maxP = -1;
for (int i = 0; i < length; i++) {
int j = numberOf(array[i], array, length);
if (j > maxA) {
maxA = j;
maxP = i;
} else if (j == maxA && array[maxP] > array[i]) {
maxP = i;
}
}
return array[maxP];
}

Answer 2

Your code has a series of errors. Some of them:
You don´t need (in this case) to use spaces in scanf. This is causing a reading error.
You don't need to pass an array address to a function in order to alter its values. Arrays are always passed by reference. So change your function from void sort(double*[],int); to void sort(double[],int);, make the necessary corrections inside the function and call it using sort(arr,l); instead of sort(&arr,l);
Your min() function declares an uninitialized variable minP, so this variable contains garbage from your memory. The for() loop isn't entering none of the both if() conditions, so your function ends and returns the still uninitialized variable minP. This random value is then used to access an index in your array: j = min(0, arr, l); min returns an random number and then arr2[i] = arr[j]; accessing forbidden memory region, which is causing your segmentation fault error. The same problem is occurring with the variables maxP and maxA in the mode() function.
You must always be careful when accessing your arrays to not go beyond its bounds and always be sure that variables will be initialized when using them. And as others have commented, I also highly recommend you to learn how to debug your programs, since this will help you to analyze its execution and trace bugs.