CODEWITHSUNDEEP
c
RoseCoder
RoseCoder

Reputation: 1

So, I am trying to write a pop function in c. My teacher says use the pointer for the top of the stack to find the element to return

#include <stdio.h>
#include <stdlib.h>
 
//**ptp just means it's a pointer point to a pointer...
void Push(int *top, int element,int **ptp){

    *top = element;
    //since *top is our pointer we use it to take whatever is in the element and store on the top.
    //top is a location in memory not a number lol, first empty space 
    
    (*ptp) ++;
    //this will add to our ptp(since it will incriment and move us to the next value rather than adding to the value.) when I call push
    //ptp will never move but it will change the values 
}

Top(int* top, int** ptp) {

    //use the pointer to point to the first number in the stack


    return *--top;
    // the star says give me the value at the point before top
}

Pop(int*top, int**ptp){

   if (*top == *ptp) {

   printf("There is no top");

   // do something to report stack underflow
}
else {
    return (*ptp--);

    return *-top;
     }



#include <stdio.h>

main()
{
    int Stack[4];
    //creates an array with 4 element 
    int* top = Stack;
    //pointer to the start of that memory 

    //step one create a push to add elements to our stack
    
    Push(top, 12, &top);
    //push is adding things
    Push(top, 34, &top);
    Push(top, 888, &top);
    Push(top, 999, &top);
     
    Pop(top,&top);

    printf("This is the top: %d \n", Top(top, &top));

    for (int i = 0; Stack[i] != Top(top, &top); i++) {
        printf("%d , ", Stack[i]);
//This will print our list 

    }       
}

Also coded an attempt at the pop function I made and was able to pop the top of my stack however the top wouldn't update to read the new top of the stack. So I have [12,34,888,999] and then I run my now deleted pop function it would have returned [12,34,888] but the top is still 999. It's weird because I deleted my pop function but when I run my code it still is in effect.

Upvotes: 0

Views: 61

Answers (1)

gnasher729
gnasher729

Reputation: 52538

For a stack, you need the actual storage area, a pointer to the complete storage area, and a pointer or an index that tells you where the last pushed element is.

It’s best not to use individual variables but a struct containing all the things you need.

Upvotes: 1

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