Question:
What is stack?
Answer:
A stack is a list of element in which elements are added to the list in
one end at the top of the stack.
That means it is an ordered group of homogeneous items of elements.
Elements are added to and removed from the top of the stack (the
most recently added items are at the top of the stack).
The last element to be added is the first to be removed and first
element will be removed in last. That is why stack is called LIFO
à Last in First Out
OR
Stack
is a special type of data structure where elements are inserted from one end
and elements are deleted from the same end. The position from where elements a
are inserted and from where elements are deleted
is
termed as top of the stack. Thus stack is a homogeneous collection of elements
of any one type, arranged linearly with access at one end only.
Stack
is also called the LIFO. That means Last On First Out. Which elements enter to
the stack at last, will out first from the stack.
Stack has basically two functions.
1. Push( )
2. Pop( )
Stack push() method:
|
|
 |
Before push the value stack top
was = 5 || After push 20 the stack, now top is 20
Stack pop() method:
Before pop the stack top was = 5 ; After
pop of the stack the top will be popped and now top = 7
For clearing the stack all code please follow the following instruction. Just stay with me only 20 minutes. I think stack's idea will be clear to you.
Stack full source code:
#include<stdio.h>
#include<stdlib.h>
#define
MAX 100
struct stack{
int data[MAX];
int top;
};
typedef struct
stack Stack;
Stack s;
//Functions
void push(int value);
int pop();
void display();
int getCount();
//main()
method starts here
int main(
){
int chose, pushValue;
s.top = -1;
printf("\n\t\t\tStack\t\t\t");
printf("\n\t\tPress
1 for Push a value\n\t\tPress 2 for pop a value\n\t\tPress 3 for displaying
total values\n\t\tPress 4 for total size\n\t\tPress 0 to exit");
printf("\n-----------------------------------------------------\n");
while(1){
printf("Enter your option : ");
scanf("%d", &chose);
switch(chose){
case 1:
printf("Enter a value to push in the stack : ");
scanf("%d", &pushValue);
push(pushValue);
break;
case 2:
pop();
break;
case 3:
display();
break;
case 4:
printf("The total element in the stack is : ");
getCount();
break;
case 0:
printf("Program exited successfully\n\n");
return 0 ;
break;
default:
printf("Please chose a value from given option\n");
}
}
}
//Functions
void push(int value){
if(s.top == (MAX -1)){
printf("Sorry stack is full\n");
}else{
s.top++;
s.data[s.top] = value;
printf("\tValue inserted
successfully\n");
}
}
int pop(){
int popValue, i;
if(s.top
== -1){
printf("Their is no value to pop\n");
}else{
popValue =
s.data[s.top];
printf("The
element %d is popped from the stack successfully\n", popValue);
s.top--;
return popValue;
}
}
void display(){
int printvalue, i;
if(s.top
== -1){
printf("Sorry stack is empty\n");
}else{
printf("The total stack is : ");
for(i = s.top; i >=0; i--){
printvalue = s.data[i];
printf("%d\t", printvalue);
}
}
printf("\n");
}
int getCount(){
int count
= 0,
i;
for(i = s.top; i >=0; i--){
s.data[i];
count++;
}
printf("%d\n", count);
return count;
}
Explanation:
Create a stack as a struct data type: we
are not making it using array. We can also do that. But here we’ve just done it
using struct. Just look it, I think I think, your stack idea will must be
clear.
Step 1: Creating a struct named stack . We put
them a top and a maximum data limit with array.
struct stack{
int data[MAX];
int top;
};
typedef struct
stack Stack;
Stack s;
Step 2: Declare the function list:
//Functions
void push(int value);
int pop();
void display();
int getCount();
Step 3: Use a while loop and a switch case
statements to evaluate our all methods which we want.
//main() method starts here
int main( ){
int chose, pushValue;
s.top = -1;
printf("\n\t\t\tStack\t\t\t");
printf("\n\t\tPress
1 for Push a value\n\t\tPress 2 for pop a value\n\t\tPress 3 for displaying
total values\n\t\tPress 4 for total size\n\t\tPress 0 to exit");
printf("\n-----------------------------------------------------\n");
while(1){
printf("Enter
your option : ");
scanf("%d", &chose);
switch(chose){
case 1:
printf("Enter
a value to push in the stack : ");
scanf("%d", &pushValue);
push(pushValue);
break;
case 2:
pop();
break;
case 3:
display();
break;
case 4:
printf("The
total element in the stack is : ");
getCount();
break;
case 0:
printf("Program exited
successfully\n\n");
return 0 ;
break;
default:
printf("Please
chose a value from given option\n");
}
}
}
Step 4: Stack push method or insert data method:
We have to push a value in the stack. Look
at the main file here we see that we first initialize the top = -1 ..By,
s.top = -1;
We
know that we have to insert value or keep value at the top of the end. So, our
previous top = -1 . and now if we make top++ , that means top = top + 1; then
top = -1 + 1 = 0 . So, now the position of
top of stack is : 0
And
the value will be set as the top of the stack. And then keep the to the array
data[] = value or s.data[s.top]
= value;
our parameter value which we passed from the main
method. So, see the code:
void push(int value){
if(s.top == (MAX -1)){
printf("Sorry
stack is full\n");
}else{
s.top++; //make top++, previous was s.top = -1
s.data[s.top]
= value;
printf("\tValue inserted
successfully\n");
}
}
Step 5: stack pop method:
Now we want to remove the top value from
the stack that is called pop
of stack. So, now
after pushing a value in the stack top index = 0 . Now we have to make the top
= top – 1 ‘s index’s value. So just do the code:
int pop(){
int popValue, i;
if(s.top == -1){
printf("Their
is no value to pop\n");
}else{
popValue = s.data[s.top];
printf("The
element %d is popped from the stack successfully\n", popValue);
s.top--;
return popValue;
}
}
Step 6: Display the stack
For displaying the stack. We need a loop must. Create
a for loop as your choice. We need t start the loop top’s index’s value. Which
is : s.top And we’ll continue the loop
until top’s index’s greater than or equal to 0 which is i >=0 And then make
decrement operator i--
for(i = s.top; i >=0; i--){
void display(){
int printvalue, i;
if(s.top == -1){
printf("Sorry
stack is empty\n");
}else{
printf("The
total stack is : ");
for(i = s.top; i
>=0; i--){
printvalue =
s.data[i];
printf("%d\t", printvalue);
}
}
Step 7: Get count method:
It is the same as the display stack. Just create a new
count variable. If an element found loop will execute of that exact time. Thus
if 6 elements in the stack then loop will execute 6 times and we
Store that count making count = count + 1 || or count++
int getCount(){
int count =
0, i;
for(i = s.top; i
>=0; i--){
s.data[i];
count++;
}
printf("%d\n", count);
return count;
}
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