Design and implement a stack class (i.e. struct with accompanying functions) in C language. The interface should allow storing any data type including complex structures (strings, int, float, etc). You can use malloc and free functions.

Sample:

// create a stack of capacity 5 with char data type

struct stack *st = newStack(5,CHAR);

st.push('a');

st.push('b');

// create a stack of capacity 5 with INTEGER data type

struct stack *st2 = newStack(5,INTEGER);

st2.push(3);

st.push('5);