#include 
     
      #include 
      
       typedef char stack_element_t;typedef struct stack_node_s{    stack_element_t element;    struct stack_node_s *restp;}stack_node_t;/*Stack top pointer*/typedef struct{    stack_node_t *topp;}stack_t;void push(stack_t *sp, stack_element_t c){    stack_node_t *newp;        /*Creates and defines new node*/    newp = (stack_node_t*)malloc(sizeof(stack_node_t));    newp->element = c;    newp->restp = sp->topp;        /*Renew stack top pointer*/    sp->topp = newp;}stack_element_t pop(stack_t *sp){    stack_node_t *to_freep;    stack_element_t ans;        to_freep = sp->topp;    ans = to_freep->element;    sp->topp = to_freep->restp;    free(to_freep);        return ans;}int main(void){    stack_t s = {
   0};        push(&s, '2');    push(&s, '+');    push(&s, 'C');    push(&s, '/');        printf("\nEmptying stack: \n");    while(s.topp != NULL)        printf("%c\n", pop(&s));            return 0;    }