Stack implementation using linked list

Stack_LL.c

#include<stdio.h>
#include<stdlib.h>

//prottyping
void push(int);
int pop(void);
void traverse(void);
int length(void);
void delete(void);
//initialize
struct node {
  int data;
  struct node* link;
};

struct node * top = NULL;
int capacity;

//-------------------------------------------------------------------------------------------
int main(){
  printf("Enter capacity of stack : ");
  scanf("%d",&capacity);
  
  while(1){
    printf("\nStack operations\n");
    printf(" 1. Push \n 2. Pop \n 3. Traverse \n 4. Length \n 5. Empty the stack \n 6. Exit");
    int option;
    printf("\nEnter your choice : ");
    scanf("%d",&option);

    switch (option)
    {
      case 1 : {if (length() >= capacity){
                  printf("\n Stack overflow\n");
                }
                else{
                  
                  printf("\nEnter push data : ");
                  int data;
                  scanf("%d", &data);
                  push(data);
                }
                break;}

      case 2 : {int temp;
                temp = pop();
                if(temp){
                  printf("\nPopped successfully\n");
                }
                else{
                  printf("\nStack underflow\n");
                }
                break;}

      case 3 : traverse();
               break;

      case 4 :{int len;
               len = length();
               if (len == 0){
                 printf("\nStack underflow\n");
               }
               else{
                printf("\nTotal elements in Stack : %d\n", len);
               }
               break;}
      
      case 5 : delete();
               break;
      
      case 6 : delete();
               exit(0);
               break;
    
      default: printf("\nInvalid input\n");
               break;
    }
  }
  return 0;
}
//-------------------------------------------------------------------------------------------

void push(int data){  
  struct node * temp;
  temp = (struct node *)malloc(sizeof(struct node));
  temp -> data = data;
  if(top == NULL){
    top = temp;
    temp -> link = NULL;
  }
  else{    
    temp -> link = top;
    top = temp;    
  }
}
//-------------------------------------------------------------------------------------------

int pop(){
  if (top ==  NULL){
    return 0;
  }
  else{
    struct node* temp;
    temp = top;
    if (temp -> link == NULL){
      top = NULL;
      free(temp);
    }
    else{
      top = temp -> link;
      temp -> link = NULL;
      free(temp);
    }
    return 1;
  }
}
//-------------------------------------------------------------------------------------------

void traverse(){

  struct node* temp;
  
  temp = top;
  if (top == NULL){
    printf("\nStack underflow\n");
  }
  else{
    printf("\n");
    while(temp != NULL){
      printf("%d  ", temp -> data);
      temp = temp -> link;
      
    }
    printf("\n");
  }
}
//-------------------------------------------------------------------------------------------

int length(){

  struct node* temp;
  int count = 0;
  temp = top;
  if (top == NULL){
    return 0;
  }
  else{
    
    while(temp != NULL){      
      temp = temp -> link;
      count++;
    }
   return count;
  }

}

void delete(){
  if (top ==  NULL){
    printf("\nStack underflow\n");
  }
  else{
    struct node* temp;
    temp = top;
    if (temp -> link == NULL){
      top = NULL;
      free(temp);
    }
    else{
      while (temp ->link ==  NULL){
        top = temp -> link;
        temp -> link = NULL;
        free(temp);
      }
      free(temp);
      top = NULL;
    }
     printf("\nStack cleaned successfully\n");
  }
}