How can I perform multiplication without the '*' operator?

Question

I was just going through some basic stuff as I am learning C. I came upon a question to multiply a number by 7 without using the * operator. Basically it\'s like this

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Answer 1

By making use of recursion, we can multiply two integers with the given constraints.

To multiply x and y, recursively add x y times.

     #include
     /* function to multiply two numbers x and y*/
     int multiply(int x, int y)
     {
        /* multiplied with anything gives */
        if(y == 0)
        return 0;

        /* Add x one by one */
        if(y > 0 )
        return (x + multiply(x, y-1));

        /* the case where y is negative */
        if(y < 0 )
        return -multiply(x, -y);
     }

     int main()
     {
       printf("\n %d", multiply(5, -11));
       getchar();
       return 0;
     }