How many pointers can be used in a c program?

Answer 1

Answergenerally we use simple pointer, void pointer,null pointer, structure pointer. Answerzero or more (unlimited).

Answer 2

A pointer is a variable. Like any other variable, it consumes memory (4 bytes on a 32-bit system). So you can have as many pointers as you like, with as many levels of indirection as you like, the only limit being dictated by available memory (which can never exceed 4GB on a 32-bit system).

Pointer-to-pointer variables are no different to pointer variables (and therefore have the same limitation as pointer variables), except that a pointer variable points to a non-pointer variable (such as int) whereas a pointer-to-pointer variable points to a pointer variable of the same type (which, in turn, points to a non-pointer variable of the same type). In other words, pointer-to-pointer variables add an extra level of indirection. You can also indirect pointer-to-pointer variables via pointer-to-pointer-to-pointer variables, and so on.

Pointer indirection is useful because, without them, pointers would always be passed to functions by value (never by reference). Passing by value copies the pointer variable, which means you can mutate the memory it points to, but you cannot change where it points (because that would only affect the copy, not the original pointer that was passed).

To pass a pointer by reference you must pass the pointer indirectly, via a pointer-to-pointer, which is itself passed by value. This allows the function to mutate the pointer variable (changing where it points), as well mutating the memory it points to.

Indirect pointers are also useful when allocating dynamic multi-dimensional arrays because each additional dimension requires an additional level of indirection.