c++ insertion sort error - c++

Question

When I compile, it gives error of read access violation. Other stack overflow posts says this is due to an infinite loop. I also saw that the value goes to a very large negative number. My guess is that it is because list[-1], but I do not know how to change it so it does not go past list[0].
Insertion sort code
void insertion_sort(int list[], int length) {
for (int i = 1; i < length; i++) {
for (int j = i; (j > 0) && (list[j] < list[j - 1]); j--) {
swap(list, list[j - 1], list[j]);
}
}
}
Swap function code
void swap(int list[], int & src, int & dest){
int temp = list[src];
list[src] = list[dest];
list[dest] = temp;
}

Answer 1

You are using the values of your sort as an index in your swap. Keep it simple.
This works.
void insertion_sort(int list[], int length) {
for (int i = 1; i < length; i++) {
for (int j = i; (j > 0) && (list[j] < list[j - 1]); j--) {
std::swap( list[j - 1], list[j] );
}
}
}
int main( )
{
int arr[ 100 ];
for( size_t i= 0; i < 100; ++i )
arr[ i ]= std::rand( );
insertion_sort( arr, 100 );
return 0;
}
Added:
As this looks like a class exercise. What you want to notice is that std::swap has no idea that your list exists. All it wants to know is what values you want to swap. So if you can't use the standard library, write your swap like the standard.

Answer 2

void insertion_sort(int list[], int length) {
for (int i = 1; i < length; i++) {
j = i;
while(j > 0 && list[j - 1] > list[j]){
swap(list, list[j], list[j-1]);
j--;
}
}
This should work for sorting least to greatest. The while loop does the job of checking if it needs to be swapped and checks the already "sorted" positions in the array if it needs to be swapped again.
Happy Coding.