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#include <stdio.h>

#include <stdlib.h>                             //for the system() and exit() functions

#define STACKSIZE 100                           //the stack size

struct STACK {                                  //stack structure
        short int top;
        int items[STACKSIZE];
};

typedef struct STACK stk;                       //a short-hand for the stack

int empty(stk *ptr){                            //checks if the stack is empty
        return(ptr->top<0?1:0);                 //shorter and makes more sense than the IF statment
}

int full(stk *ptr) {                            //checks if the stack is full
        return(ptr->top>=STACKSIZE?1:0);        //read above
}

void push(stk *ptr, int *x , short int *top) {                  //pushs a value to the top of the stack
                ptr->items[++(*top)]=*x;
                /*Doing ptr->items[++ptr->times]; takes
                 * time and make it so complicated for the reader
                 * Just refernce the top element in the stack
                 * rather than accesing structure twice
                 */
                printf(">>Stack Layer %d\n",(*top)+1);
}

int pop(stk *ptr , short int *top ) {           //displays the top value of the stack
                printf(">>Stack Layer %d\n",((*top))+1);
        /* The User Will Never Like The Idea of
         * StacK Layer 0 :D
         */
        return (ptr->items[(*top)--]);
        /* Same as before */

}

void print_pop(stk *ptr){       //the pop() function but with empty() check and messages
        if(empty(ptr))
                puts(">>The stack is empty!");
        else
                printf(">>The last value in the stack is: %d.\n", pop(ptr , &ptr->top ));
}

void print_push(stk *ptr){      //the push() function with the checking and messages
        int x;
        if(full(ptr))
                puts(">>The stack is full!");
        else{
                printf(">>Enter the value you want to push: ");
                fflush(stdin);
/*to clear the standard input and prevent a weird behavior,
although i been told it's not THE way 2 do it*/
                scanf("%d", &x);
                push(ptr, &x , &ptr->top);
                puts(">>done!");
        }
}

void print_all(stk *ptr) {                      //prints all the elements in the stack
        short int i;
        /* if you say i=0 it will start from the beggining of the stack
                                          not the top of the stack
                                          remember First in last out
                                          */
        system("cls");/* What if someone have a linux box like me :S */
        puts("********************");
        if (empty(ptr))
                puts(">>The stack is empty!");
        else{
                /* You soppuse to start from the top */
                for ( i = ptr->top ; i >=0 ; i--)
                printf("|%d- %d\n",i+1, ptr->items[i]);
        }
        puts("********************");
}


void interface(stk *ptr) {      //the "interface" lol, i KNOW it's a console aplication :D
        unsigned short int choice;              //we only need numbers from 1 to 4
        system("cls");
        puts("\n=====================================");
        puts("Stack Implementation in C...");
        puts("=====================================");
/*BEGINING:*/
        /* Why there is loops ??
         * Using GOTO stetement is danger in debuging
         * you will have no idea where in the program is flowing to this
         * lable
         */
        while(1)
        {

                puts("\n=======================================================");
                puts("1- Press 1 for putting a value in the stack.");
                puts("2- Press 2 for displaying the last value in the stack.");
                puts("3- Press 3 for displaying ALL the values in the stack.");
                puts("4- Press 4 for exiting the program.");
                puts("=======================================================");
                printf("What do you want to do? ");
                fflush(stdin);          //read above
                /* Flushing Stdin Is Wrong
                 * Read man fflush
                 * use a functin like getchar();
                 */
                scanf("%d", &choice);
                puts("");               //new line
                switch (choice) {
                        case 1:
                                print_push(ptr);
                                break;
                        case 2:
                                print_pop(ptr);
                                break;
                        case 3:
                                print_all(ptr);
                                break;
                        case 4:
                                exit(1);
                                /* You Are Missing A Break Here man :D*/
                                break;
                        default:
                                puts(">>Please make sure you've entered a valid option..(1-4))");
                                        break;
                }
        }
        /*goto BEGINING;        //repeat again and again til the user exits*/
}

int main() {                            //finaly the main :D
        stk stack;
        stack.top=-1;                   //sets the top to -1 for the stack to act right
        interface(&stack);
        return 0;
}

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////////////

void push(stk *ptr, int *x) {                  //pushs a value to the top of the stack
                ptr->items[++(ptr->top)]=*x;                
                printf(">>Stack Layer %d\n",(ptr->top)+1);
}

int pop(stk *ptr) {           //displays the top value of the stack
         printf(">>Stack Layer %d\n",((ptr->top))+1);        
         return (ptr->items[(ptr->top)--]);        

}

///////////////////