Dynamic Memory Allocation In C | C Memory Management Explained | C For Beginners | Simplilearn

Summary

This educational video by Simply Learn introduces memory management in C programming. It explains the difference between static and dynamic memory allocation, emphasizing the flexibility of the latter for runtime memory needs. The video covers functions like malloc, calloc, realloc, and free from the stdlib.h library, illustrating how they allocate, initialize, resize, and deallocate memory blocks. Practical examples and syntax are provided, along with a simple program demonstration, ensuring viewers grasp the concepts for efficient memory usage in C.

Takeaways

• 😀 Memory management in C involves strategies for allocating and deallocating memory during the program's execution.
• 📚 There are two primary methods for memory allocation in C: static memory allocation and dynamic memory allocation.
• 🔧 Static memory allocation assigns memory to variables at compile time with a fixed size that cannot be changed.
• 💾 Dynamic memory allocation occurs at runtime, allowing for more flexibility as memory can be allocated and deallocated as needed.
• 🔑 The C standard library provides functions like `malloc`, `calloc`, `realloc`, and `free` for dynamic memory management.
• 📝 The `malloc` function is used to allocate a single block of memory, and it returns a pointer to the beginning of the block.
• 🔑 The `calloc` function allocates memory for an array, initializing all elements to zero, and requires two arguments: number of elements and size of each element.
• 🔄 The `realloc` function is used to resize a previously allocated block of memory without losing the original data.
• 🗑️ The `free` function is essential for deallocating memory that is no longer needed, making it available for other programs to use.
• 💻 The video includes a practical demonstration of using these functions, highlighting the importance of checking for memory allocation success and proper memory deallocation.

Q & A

What is memory management in C programming?

Memory management in C programming refers to the process of allocating and deallocating memory during runtime to manage the memory more efficiently. It involves allocating memory dynamically to variables whose size is not known until runtime.

What are the two ways to allocate memory in C?

The two ways to allocate memory in C are static memory allocation and dynamic memory allocation. Static allocation happens during compile time, while dynamic allocation occurs during runtime.

How does static memory allocation differ from dynamic memory allocation?

In static memory allocation, the memory is allocated during compile time and the size is fixed, whereas in dynamic memory allocation, memory is allocated during runtime and its size can change as needed.

What functions are provided by C for dynamic memory allocation?

C provides the functions malloc(), calloc(), realloc(), and free() for dynamic memory allocation. These functions are defined in the stdlib.h header file.

What is the purpose of the malloc() function in C?

The malloc() function is used to allocate a block of memory of a specified size. It returns a pointer to the beginning of the block, which can be used to access the allocated memory.

How does the calloc() function differ from the malloc() function?

The calloc() function is similar to malloc() but it allocates memory for an array of elements, initializing all of them to zero. It takes two arguments: the number of elements and the size of each element.

What is the role of the realloc() function in memory management?

The realloc() function is used to resize a previously allocated block of memory. It can be used to either increase or decrease the size of the memory block without losing the existing data.

Why is the free() function necessary in C?

The free() function is necessary to deallocate memory that was previously allocated by malloc(), calloc(), or realloc(). It helps in returning the memory back to the heap for reuse by other programs, thus preventing memory leaks.

What happens if malloc() fails to allocate memory?

If malloc() fails to allocate memory, it returns a null pointer. It's important to check the return value to ensure that memory allocation was successful before using the allocated memory.

What is the significance of checking the return value of memory allocation functions?

Checking the return value of memory allocation functions is significant because it allows the programmer to handle errors, such as memory allocation failure, gracefully. It prevents the program from using uninitialized memory, which can lead to crashes or undefined behavior.

Outlines

00:00

💾 Introduction to Memory Management in C

This paragraph introduces the topic of memory management in C programming. It explains the difference between static and dynamic memory allocation. Static allocation assigns memory during compile time with a fixed size, while dynamic allocation occurs at runtime and allows for variable memory sizes. The paragraph sets the stage for a deeper exploration of dynamic memory allocation, mentioning functions like malloc, calloc, realloc, and free from the stdlib.h library. It also provides a brief overview of the syntax and examples that will be covered in the video.

05:03

🔧 Practical Examples of Dynamic Memory Allocation

This paragraph delves into practical examples of using dynamic memory allocation functions in C. It demonstrates how to check for memory availability, allocate memory using malloc, and deallocate it using free. The paragraph also shows an error scenario where calloc is used with only one argument, illustrating the importance of providing the correct number of arguments. The video concludes with a successful execution of calloc after correcting the error, highlighting the output of the program. The paragraph wraps up with a call to action for viewers to subscribe and engage with the channel for more informative content.

Keywords

💡Memory Management

Memory management refers to the process of allocating and deallocating memory during the execution of a program. In the context of the video, memory management in C programming is crucial as it allows for the efficient use of memory resources. The video explains that memory is automatically allocated to program variables at compile time, but sometimes, dynamic allocation is necessary to change the size of an array or to reallocate memory during runtime.

💡Static Memory Allocation

Static memory allocation is a method where memory is assigned to variables during compile time with a fixed size that does not change throughout the program's execution. The video highlights this as one of the two ways to allocate memory in C, contrasting it with dynamic memory allocation, which is performed at runtime.

💡Dynamic Memory Allocation

Dynamic memory allocation allows memory to be allocated during runtime, which is useful when the size of the data is unknown until the program is running. The video emphasizes its importance for managing memory more efficiently, as it enables the allocation and reallocation of memory blocks as needed.

💡Heap Memory

Heap memory is a region in memory where dynamically allocated memory is stored. The video mentions that dynamic memory allocation involves allocating memory blocks from the heap when required, and these blocks can be returned to the heap for reuse once they are no longer needed.

💡malloc Function

The malloc function is used in C to allocate a block of memory dynamically. The video provides the syntax and an example of how to use malloc, explaining that it takes the size of the memory required as an argument and returns a pointer to the first byte of the allocated block.

💡calloc Function

The calloc function is similar to malloc but initializes the allocated memory to zero. The video explains that calloc takes two arguments: the number of elements and the size of each element, and it is used when multiple blocks of memory need to be allocated and initialized.

💡realloc Function

The realloc function is used to resize a previously allocated block of memory. The video demonstrates how realloc can be used to change the size of an array without losing the existing data, which is particularly useful when the new size is unknown until runtime.

💡free Function

The free function is used to deallocate memory that was previously allocated using malloc, calloc, or realloc. The video stresses the importance of using free to return memory to the heap once it is no longer needed, which helps in efficient memory usage and prevents memory leaks.

💡Pointer

A pointer in C is a variable that holds the memory address of another variable. The video explains that pointers are used to hold the address of the first element in a block of memory allocated by malloc, calloc, or realloc, and they are essential for accessing and managing dynamically allocated memory.

💡Memory Leak

A memory leak occurs when allocated memory is not released back to the system after it is no longer needed. While not explicitly mentioned in the video script, the concept is relevant as the video discusses the importance of using the free function to avoid memory leaks by deallocating memory once it is no longer in use.

Highlights

Introduction to memory management in C programming.

Explanation of static memory allocation during compile time.

Discussion on dynamic memory allocation at runtime.

Difference between static and dynamic memory allocation.

Efficient memory management using dynamic allocation.

Introduction to C functions for dynamic memory allocation: malloc, calloc, realloc, and free.

Syntax and example of the malloc function.

How malloc checks for available memory and returns a pointer.

Syntax and example of the calloc function for allocating memory with zero-initialized values.

Explanation of the realloc function for resizing memory blocks.

Use case of realloc when needing to change array size without data loss.

Syntax and example of the free function for deallocating memory.

Importance of freeing memory to allow other programs to use it.

Running a simple program to demonstrate memory allocation and deallocation.

Error handling when using calloc with incorrect arguments.

Conclusion and summary of the session on C memory management.

Call to action for subscribing to the Simply Learn YouTube channel.

Transcripts

hey guys welcome to yet another

interesting and informative video by

simply learn in today's video we're

gonna be learning all about memory

management insane but before we begin if

you haven't subscribed to our channel

already make sure to hit the subscribe

button and the bell icon to never miss

an update so now without any further

delay let's begin

this session will help you to understand

what is memory management in c

later we will discuss dynamic memory

allocation and function used to allocate

memory dynamically with the help of

syntax and examples

so now let's begin with what memory

management in c is

as we all know in c programming the

memory is automatically allocated to all

the program variables during compile

time

so sometimes to reallocate the memory or

to change the size of an array we must

allocate memory during runtime and we

have two ways to locate memory

and they are static memory allocation

and dynamic memory allocation

in static memory allocation the memories

are located during compile time and the

fixed size of memory will be assigned to

the variables

moreover there won't be any change in

the memory size and location and in the

case of dynamic memory allocation the

memories are located during runtime

so now let us try to understand more

about dynamic memory allocation

to manage the memory more efficiently we

use dynamic memory allocation

unlike static allocation the memories

are located during run time in dynamic

memory allocation

and the allocated memory is not constant

or fixed we can allocate the memory

blocks from the hip whenever required

when the memory block is no longer in

use we can also return the block of

memory to the hip for reuse by another

program

and in addition to this we can also

reallocate the block of memory space

when required to allocate memory

dynamically c provides a set of

functions and they are emblock clock

reallock and free functions that are

defined in the stdlib dot hedge that is

standard library header file

let's look at the syntax and examples of

this function

first when we use the mlog function the

continuous block of memory will be

allocated and the point of variable will

hold the address of the first element

now let's look at the below given syntax

the mlog function take one argument

memory size for example

if we require 10 bytes of memory size we

can mention 10 or we can mention the

size of int

the mlog function will first checks

whether the continuous memory is

available on the hip and if free memory

is unavailable the function will return

a 0 or a null value

else it will allocate the memory as per

the requested size if memory is

available

and the pointer will point to the

address of the first element in the

block

next we have clock function

the syntax is pointer variable is equal

to c log of number element comma memory

size for example we have 10 as a number

element and the element size is the size

of int

clr function is similar to the mlog

function but in case of clr function

multiple blocks of memory of the same

size will be allocated which holds 0

value by default and it takes 2

arguments that is number element and

element size

up next we have reallock function

first let us look at the syntax

pointer variable is equal to reallock

pointer variable comma memory size

in real lock function we pass point of

variable as an argument and the memory

size for example

real lock pointer variable ptr comma the

size of it

so sometimes it becomes very difficult

to change the array size when we have to

store new values into the array or to

copy into the larger size array so in

that case we use real log functions to

change the array size without losing the

data in short the real of function will

change the size of the previously

allocated block of memory

i hope you got a good understanding of

why we use real log function

moving ahead we have free function

syntax is simple we pass pointer in free

function like for example free ptr the

free function is used to deallocate the

memory space occupied by the previously

allocated by mlog c a lock or rear lock

functions

in order to use the memory more

efficiently and to return back the

memory to the hip once done we use free

function

once we free the memory other programs

can use that block of memory if required

now let's run simple program using this

function

so in this particular example we have

included the standard library header

file

that is stdlib.h and then mlog function

and using if condition we're gonna check

whether memory is available or not and

if memory is available it gonna locate

the memory and print the value of 10.

and finally we have used free function

to deallocate the memory so now let's

run it

as you all can see the value 10 is

printed successfully

now using same program let's use clock

function so instead of mlog let's give

cllo

and since we have passed only one

argument that is sizeof end let's

execute the program and see what would

be the

error as you can see the error

it says that too few arguments to

function see alok

it means that the clock function will

take two arguments so let's give the

number element

so save the program

and

run it

and here we got the output

so with this we have come to the end of

this session on c memory management i

hope this session was informative and

interesting until next time thank you

stay safe and keep learning

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