CODEWITHSUNDEEP
cfunctionpointersfunction-pointers
zaira
zaira

Reputation: 29

Is Multiplication and Division of Pointers allowed in C?

I remember my programming prof said that multiplication and division of pointers are not allowed. We have a seatwork that needs us to create a program that adds, subtracts, multiplies and divides two numbers using pointers.

This is my code in the main function:

float num1, num2, a, b, c, d;

printf("Enter a number: ");
scanf("%f", &num1);
printf("Enter another number: ");
scanf("%f", &num2);

a = add(&num1, &num2);
b = subtract(&num1, &num2);
c = multiply(&num1, &num2);
d = divide(&num1, &num2);

printf("Sum: %.2f\nDifference: %.2f\nProduct: %.2f\nQuotient: %.2f", a, b, c, d);
getch();
return 0;

This is my code for the add, subtract, multiply, and divide functions:

float add(float *x, float *y)
{
    return *x+*y;
}
float subtract(float *x, float *y)
{
    return *x-*y;
}
float multiply(float *x, float *y)
{
    return *x * *y;
}
float divide(float *x, float *y)
{
    return *x / *y;
}

My code runs and works but is it allowed?

Upvotes: 2

Views: 14105

Answers (2)

Ardent Coder
Ardent Coder

Reputation: 3995

Multiplication and division of pointers are not allowed in C.

For example,

int *ptr1, *ptr2, *ptr3;

ptr3 = ptr1 * ptr2; // Error: Multiplication of pointers

ptr3 = ptr1 / ptr2; // Error: Division of pointers

This discussion is worthwhile to know the reasons behind this restriction on pointers in C.

Getting into your code, it works because you are not multiplying or dividing any pointers but multiplying and dividing the values pointed by those pointers as you have used the dereference operator.

For example,

int a = 1, b = 2, c = 3;

int *ptr1 = &a;

int *ptr2 = &b;

int *ptr3 = &c;

*ptr3 = *ptr1 * *ptr2; // No error: c = a * b

*ptr3 = *ptr1 / *ptr2; // No error: c = a / b

See: meaning of "referencing" and "dereferencing"

Upvotes: 7

dev7060
dev7060

Reputation: 120

*x and *y refer to the values pointed by them, not the pointers.

*x * *y -> allowed.

x * y -> not allowed.

Upvotes: 4

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