This document discusses the differences between the stack and heap in computer memory. The stack stores function parameters and local variables sequentially and follows LIFO order. The heap is reserved for dynamic memory allocation using malloc() and freed using free(). The stack has faster access but limited size, while the heap has no size limit but slower access and requires manual memory management. Examples are provided to illustrate how variables are stored in each.

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Functions With Heap And Stack

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4. • Stores a set of elements in a sequential order
• Stack principle: LAST IN FIRST OUT (LIFO)
• It means: the last element inserted, is the first one to be
removed
Which is the first element to pick up?
The Stack
Example

5. • When a function declares a new variable, it is
pushed onto the stack.
• And when it exits, all of the variables pushed by
that function, are freed (means deleted).
• So that region of memory becomes available for
other stack variables.
Stack in functions

6. public int factorial (int x)
{
if (x > 1)
{
//recursive case:
return factorial(x-1) * x;
}
else /*base case*/
return 1;
}
Factorial(3){
If(3>1){
return factorial (2)*3
Factorial(2){
If(2>1){
return factorial (1)*2
Factorial(1){
If(1>1){
return 1;
Example of Stack in recursive function
1
2
Final output: 6

7. Example for Stack
#include <stdio.h>
double multiplyByTwo (double input) {
double twice = input * 2.0;
return twice;
}
int main (int argc, char *argv[])
{
int age = 30;
double salary = 12345.67;
double myList[3] = {1.2, 2.3, 3.4};
printf("double your salary is %.3fn",
multiplyByTwo(salary));
return 0;
}

8. The Heap
• The heap is an area of memory reserved for dynamic
memory allocation.
• Dynamic memory can be allotted by calling the malloc( )
function in C.
• When this memory is no longer needed it can be freed
up by calling free( ) .
• Once the memory is freed it can reused by future
allocations.
• The location and size of the heap are set at compile
time.

9. Example for Heap
#include <stdio.h>
#include <stdlib.h>
double *multiplyByTwo (double *input) {
double *twice = malloc(sizeof(double));
*twice = *input * 2.0;
return twice;
}
int main (int argc, char *argv[])
{
int *age = malloc(sizeof(int));
*age = 30;
double *salary = malloc(sizeof(double));
*salary = 12345.67;
double *myList = malloc(3 * sizeof(double));
myList[0] = 1.2;
myList[1] = 2.3;
myList[2] = 3.4;
double *twiceSalary = multiplyByTwo(salary);
printf("double your salary is %.3fn", *twiceSalary);
free(age);
free(salary);
free(myList);
free(twiceSalary);
return 0;
}

10. Both programs will show output as :
double your salary is 24691.340

11. Stack
• very fast access
• don't have to explicitly de-allocate variables
• space is managed efficiently by CPU, memory
will not become fragmented
• local variables only
• limit on stack size (OS-dependent)
• variables cannot be resized
Stack vs Heap Pros and Cons

12. Heap
• variables can be accessed globally
• no limit on memory size
• (relatively) slower access
• no guaranteed efficient use of space, memory may
become fragmented over time as blocks of memory
are allocated, then freed
• you must manage memory (you're in charge of
allocating and freeing variables)
• variables can be resized using realloc()
Stack vs Heap Pros and Cons

13. Doubts…?

14. thank you

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