Counting sort segmentation fault in C

Question

Below is my attempt at a counting sort. I have diagrammed my logic, run through it verbally, and commented my code thoroughly. However, my code causes a segmentation fault. I understand a segmentation fault represents an illegal access to memory, so this must mean one of my index values is trying to access an index outside of an array's range. However, I can't figure out why this is happening.

Fortunately, my debugger highlights the line below, which I've also noted in a comment, where the segmentation fault occurs. Nevertheless, I am entirely stumped. Would appreciate any help understanding the nature of this segmentation fault, thank you.

void sort(int values[], int n)
{

    //create array of finite size (65536)
    int countArray[INT_MAX];

    //create array to eventually store sorted values
    int sortedValues[n];

    //loop through unsorted values to increment countArray index for each occurrence
    for(int i = 0; i < n; i++) {
        countArray[ values[i] ] += 1;
    }


    //starting index for sortedValues[]
    int sortedIndex = 0;

    //loop until we've reached the end of sortedValues[]
    while(sortedIndex < n) {

        //loop through each index value of countArray
        //j represents the value
        for(int j = 0; j < INT_MAX; j++) {

            //how many times does the index of countArray occur in values[]?
            int c = countArray[j];

            //only add index j as a value to sortedValues[] if it appears in values[]
            while(c > 0) {

                //append j to sortedValues[]
                //--SEGMENTATION FAULT OCCURS ON THE LINE BELOW--
                sortedValues[sortedIndex] = j;

                //decrease the count of countArray[j] once value appended to sortedValues[]
                c -= 1;

                //move to next index of sortedValues[]
                sortedIndex += 1;
            }
        } 
    }
    return;
}

Answer 1

You need to initialize countArray elements to zero to fix the crash:

int countArray[INT_MAX] = {0};

However, your function is still useless, because it places sorted numbers into a local array that never makes it out of the function. In order to fix this, remove sortedValues array, and use the original values array for the output instead:

values[sortedIndex] = j;

Now the caller will see that the array he passed into your function comes back sorted.

Note: The outer loop while(sortedIndex < n) is harmless but useless, because the for loop guarantees that sortedIndex is exactly n. You should remove the while loop from your code.