How to return my string P here?

Question

int Dot_Product( int A[], int B[], int size )
{ 
     int i = 0;
     int P[size];

     while ( i <= size ) {
         P[i] = A[i] * B[i];
     }

     return P;   
}

infinite loop????? I think I just went cross-eyed. You need a way out of your loop. — PaulG, Nov 21 '13 at 21:38
Also, it should be < not <=, the latter will cause you to go out of bounds. From what I remember of C (which I wouldn't recommend as a starting language anyways) indexes are 0 based, so 0 to size - 1 — PaulG, Nov 21 '13 at 21:46

score 1 · Answer 1 · answered Nov 21 '13 at 21:41

You can't return arrays in C. You can return pointers to arrays but then you have to worry about memory management. So often, people pass arrays INTO the function to be used for assignment.

However if you're really just trying to take the dot product, you shouldn't end up with an array, you should end up with a single value, so this should suffice:

    int Dot_Product( int A[], int B[], int size )
    { 
        int i = 0;
        int product = 0;
        while ( i < size ){
            product += A[i] * B[i];
            ++i;
        }
        return product;   
     }

score 0 · Answer 2 · answered Nov 21 '13 at 22:14

C doesn't allow you to return arrays, you can pass a pointer to a function and with that pointer change the values of the array you declare in the main function.

void Dot_Product(int A[], int B[], int size, int *product) {
int i;
for(i=0; i<size; i++) 
   product[i]=A[i]*B[i];
}

How to return my string P here?

2 Answers2