#25 C Pointers and Functions | C Programming For Beginners

Summary

In this video, the instructor explores the use of pointers with functions in C programming. The tutorial covers passing pointer variables as function arguments, modifying values at memory addresses, and returning pointer values from functions. Examples include finding the square of a number and summing two integers using pointers. Additionally, viewers are assigned a task to create a multiplication function using pointers. The video emphasizes hands-on learning, offering resources like quizzes, challenges, and a GitHub repository for further practice. Engagement is encouraged through likes, comments, and subscriptions.

Takeaways

• 📌 Pointers in C can be used to pass arguments to functions, allowing the function to modify the value of a variable in the calling scope.
• 🔢 A function can accept a pointer as an argument and change the value it points to, demonstrating how pointers can affect data outside their scope.
• 💡 The script provides an example of a function that calculates the square of a number using a pointer to modify the original variable's value.
• 👨‍🏫 The tutorial explains how to use pointers to find the square of a number, emphasizing the use of pointer syntax within functions.
• 🎯 It showcases a function that returns a pointer to an integer, illustrating how functions can return addresses in addition to values.
• 🛠️ The script includes a practical example where a function adds two numbers using pointers and returns the sum through a pointer.
• 📚 The video encourages viewers to practice programming with quizzes and challenges through the introduction of a learning platform called 'Programmies Pro'.
• 🔄 The tutorial demonstrates the concept of returning a pointer from a function and how to use the returned pointer to access the result.
• 📈 The script motivates engagement by asking viewers to like, comment, and subscribe to support free content creation.
• 📝 A programming task is provided at the end of the script to reinforce learning, involving creating a function that multiplies two numbers using pointers.
• 🎉 The video concludes with a question to engage viewers, asking them to comment with the return type of a certain function.

Q & A

What is the purpose of using pointers with functions in C programming?

Pointers allow functions to directly modify the values of variables by passing their memory addresses, enabling more efficient memory use and manipulation of data.

In the example where a pointer is passed to a function, how is the value of a variable changed?

The address of the variable is passed to the function, and inside the function, the value at the memory address is changed using the pointer. This results in the original variable's value being modified outside the function.

What does the `find_square` function do in the video example?

The `find_square` function calculates the square of a number by accepting a pointer to an integer, multiplying the value pointed by the pointer with itself, and then updating the original value with the square.

How can a function return a pointer in C?

A function can return a pointer by changing its return type to a pointer type (e.g., `int*` for an integer pointer) and using the `return` statement to return the pointer. The returned pointer can then be used to access or modify the data stored at that memory address.

Why is it necessary to use an asterisk (*) before a pointer variable inside a function?

The asterisk (*) dereferences the pointer, which means it accesses the value stored at the memory address the pointer points to. Without dereferencing, the function would only access the memory address, not the actual data.

What is the difference between passing a regular variable and a pointer variable to a function in C?

When passing a regular variable, the function receives a copy of the variable's value, so changes made inside the function don't affect the original variable. When passing a pointer, the function receives the memory address, allowing it to modify the original variable directly.

In the last example, how does the function add two numbers using pointers?

The function `add_number` accepts three pointers: one for each number and one for storing the sum. It computes the sum by dereferencing the first two pointers, adds their values, and stores the result in the location pointed by the third pointer.

How is the result of a function that returns a pointer printed in the video example?

The result is printed by dereferencing the pointer returned by the function, using an asterisk (*) before the pointer variable in the `printf` statement.

What are the advantages of using pointers when returning values from functions?

Using pointers to return values allows functions to return more than one value and modify variables directly, enabling efficient memory use and bypassing the need to return copies of large data structures.

What task is given to viewers at the end of the video?

Viewers are asked to create a program that multiplies two numbers using a function and pointers. The function should accept three pointers, multiply the values pointed to by the first two, and store the result in the location pointed to by the third pointer.

Outlines

00:00

📘 Introduction to Pointers and Functions in C

The video continues a series on C programming, specifically focusing on pointers and their use with functions. It begins with a review of a function that calculates the square of a number by passing a regular variable. Then, the concept of passing a pointer to a function is introduced. An example function `find_value` is shown, which accepts a pointer, changes the value of the variable it points to, and the effect of this change is demonstrated by updating the value of a variable in the `main` function.

05:00

🧮 Computing Square Using Pointers

In this section, the script discusses another example, where the square of a number is computed using a pointer instead of a regular variable. The function `find_square` accepts a pointer as a parameter and modifies the value stored at the memory address of the number. The multiplication is performed using the dereferencing operator (`*`), and the square is assigned back to the value pointed by the pointer. The example demonstrates how pointers can be used to manipulate data efficiently within functions.

📈 Returning a Pointer from a Function

Here, the concept of returning a pointer from a function is explored. The `find_square` function is modified to return the pointer to the variable that stores the square of a number. The script explains how to handle this return value by storing it in a pointer variable and then using it to print the squared result. This illustrates how functions in C can return memory addresses and how to work with them in the `main` function.

➕ Adding Two Numbers Using Pointers

This section introduces an example of a function that adds two numbers using pointers and returns the sum. The function `add_numbers` takes three pointers as arguments: two for the numbers to be added and one to store the result. Inside the function, the values pointed to by the first two pointers are added, and the result is stored in the memory address of the third pointer. The returned pointer holds the address of the sum, which is then printed in the `main` function.

📝 Programming Task: Multiplying Numbers with Pointers

In this final segment, the viewer is given a programming task to practice using pointers with functions. The task involves creating a function that multiplies two numbers using three pointer arguments: two for the input numbers and one to store the product. The program should call the function with the addresses of three variables and print the result. A GitHub repository is mentioned as a resource for the solution, and the video ends with a quiz to reinforce the lesson.

Keywords

💡Pointers

Pointers in C are variables that store the memory address of another variable. In the video, the concept of pointers is central as it explores how to use pointers with functions to manipulate and return values directly in memory. For example, a pointer is passed to a function to modify the value of a variable without returning it explicitly.

💡Function

A function is a block of code designed to perform a specific task. In this video, functions are explained with examples that pass both regular variables and pointer variables as parameters. The video demonstrates how passing pointers to functions allows direct manipulation of memory, as opposed to just passing values.

💡Memory Address

A memory address is the specific location in memory where a variable is stored. The video frequently discusses passing memory addresses to functions using pointers, emphasizing that pointers allow functions to directly access and modify variables stored at those addresses.

💡Pass by Reference

Pass by reference means passing the memory address of a variable to a function, allowing the function to modify the original variable. In C, this is done using pointers. The video provides examples where variables are modified directly through pointers passed to functions, such as changing a number’s value within a function.

💡Dereferencing

Dereferencing a pointer means accessing the value stored at the memory address that the pointer points to. The video explains dereferencing through examples where pointer variables are used inside functions to modify the values of variables by accessing their memory addresses.

💡Return Pointer

Returning a pointer from a function allows the function to return a memory address instead of a value. The video provides examples where functions return pointers to the memory addresses of variables, enabling the caller to directly work with the memory locations of computed results, such as the square of a number.

💡Integer Pointer

An integer pointer (int *) is a pointer variable that stores the memory address of an integer variable. Throughout the video, integer pointers are used in examples where functions take pointers as arguments and return them, manipulating integers stored in memory by using the pointers.

💡Pointer Arithmetic

Pointer arithmetic involves performing operations like addition or multiplication on values pointed to by pointers. The video demonstrates this when computing the square of a number or adding two numbers by dereferencing the pointer to access and manipulate the values stored at specific memory addresses.

💡Main Function

The main function is the entry point for a C program. In the video, it is where variables are initialized and functions are called. The video shows how the main function is used to set up variables and pass their addresses to other functions to manipulate their values using pointers.

💡Print Statement

The print statement in C, typically done using printf(), is used to output values to the console. In the video, printf() is used to demonstrate how the values of variables are printed before and after being manipulated by functions using pointers, showing the effect of passing pointers on the original variables.

Highlights

Introduction to using pointers and functions together in C programming.

Explanation of a function that calculates the square of a number using regular variables.

Introduction to passing a pointer as an argument to a function in C.

Example of modifying a variable's value using a pointer inside a function.

Demonstration of how passing a pointer to a function can change the original variable's value.

Example of computing the square of a number using pointers instead of regular variables.

Explanation of using pointer dereferencing to perform operations on the value stored at the pointer’s address.

Example of returning a pointer from a function and how to store it in a pointer variable.

Explanation of modifying the print statement to show the result from a pointer variable.

Demonstration of how a function can return a pointer and how to work with it in the main function.

Example of a function that computes the sum of two numbers using pointers.

Introduction to writing a function that accepts multiple pointers to perform operations.

Explanation of passing addresses to a function and how pointer arithmetic is used within it.

Programming task for viewers: Multiply two numbers using a function and pointers.

Promotion of 'Programmy Pro' for more interactive learning, quizzes, and real-world projects in programming.

Transcripts

hey guys welcome back to this series on

c programming in the last few videos we

have been learning about pointers in c

we'll continue that in this video as

well today we will learn to use pointers

and function together this is going to

be an interesting video so let's get

started

firstly let's revise the working of the

function with the help of an example

here i have created a function that

calculates the square of a number the

function takes single parameter and it

then computes the square of the number

and then returns the square here we are

passing a regular variable to the

function

in c we can also pass a pointer variable

as an argument to a function let's see

an example in which i'll create a

function that accepts a pointer as an

argument and change the value pointed by

the pointer

so i'll create a function void

find

value here this function takes pointer

as an argument

and

inside the function

asterisk num is equals to 39.

here the non-parameter is a pointer

variable and we have changed the value

pointed by this pointer now let's create

a number variable inside the main so

i'll create here int

number

and i'll assign value 21 to this

and i'll call the function by passing

the address of the number so i'll call

the function find

value

bracket

ampersand

number

since our function accepts a pointer

variable which stores the memory address

we are passing the address of the number

variable

now let me print the value of the number

so i'll use print statement

printf

inside quotation number

percent d

comma

number

let's run this code

as you can see the value of the number

is changed to 39. this happens because

when we pass the address of a number

variable

the pointer variable inside the function

is assigned with the address of the

number

so when we change the value at the

memory address the value of the number

is also changed

now let's see another example in this

example we'll find the square of a

number like before but this time we'll

use a pointer variable instead of a

regular variable here i have the code

from our earlier program let's remove

this function

now i'll create a find square function

void

find square

and this function accepts a pointer

variable as its parameter

so

int

asterix

number

inside the function i'll find the square

of the number so int

square is equals to

asterisk number

multiplied with

number

this syntax might look confusing for you

here asterix number is the value pointed

by the number pointer and we are

multiplying the value with itself

now the square variable stores the

square of the number now let me assign

this to the value pointed by the number

pointer so

asterix number

is equals to

square

now inside the main function i'll change

this find value to find square

so find square

i'll also modify this print statement

i'll write here

square

is now i'll run this code

as you can see we have computed the

square of the number

by the way do you want to take your

programming journey to the next level

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one limitation it's hard to learn and

practice together at the same time lucky

for you we recently launched programmies

pro that provides tutorials along with

quizzes and challenges which will help

you practice and test your learning in

real time also the course includes

projects to give you an experience of

how programming works in the real world

sign up now visit this link which is

also available in the video description

below

just like regular variable we can also

return a pointer variable from a

function let me show you an example here

we have our code from our earlier

program now suppose i want to return

pointer from the function not just

compute the square so first i'll change

the return type of the function from

void

to

integer pointer that is int asterisk

now inside the function i'll add a

return statement that returns a pointer

so return

number

this statement returns the address

pointed by number

now to store the return value i'll

assign this function call to a variable

so int asterisk

result

is equals to this function call

since the return value is an address we

have created a pointer to store the

result now let's use this result

variable to print the square value

i'll modify this print statement here

i'll remove this square is

and i'll write here

result is

percent d

and i'll remove this number and i'll

write here

asterix

result

now let's run this program

as you can see the return address stores

the square of the number

okay guys we need your support to keep

these types of content free for all

users youtube really likes engagement on

the video so leave a comment below press

that like button and hit subscribe if

you haven't already let's keep the

engagement score higher so that more

people can discover and enjoy these

courses

let's see one more example to make it

more clear for you so i'll create a

function that adds to number and returns

the sum let me go back to my code editor

i'll remove these all code from here

and i'll remove these statements from

here

so first i'll create a function that

accepts three pointer so i'll create a

function here

that is int

asterisk add

number

int

asterisk

num1

comma int

asterisk

num2 comma int

asterix sum

inside the function we will compute the

sum of the number pointed by num1 and

num2 and store the result to the address

pointed by the sum

so

we'll do

asterix

sum is equals to

asterisk num1

plus

asterisk

num tube

then i'll return the sum

so return

sum

now inside the main function i'll create

two variables int number 1

and i'll assign value 32

and another variable in number 2

and i'll assign value 18 to this and a

sum variable to store the sum let me

call the function by passing the

addresses of three variables

so i'll call the function add numbers

parenthesis ampersand number 1

comma

ampersand number 2

comma

ampersand sum

since the function returns the address

i'll assign this function call to a

pointer so int

asterisk result is equals to this

function

finally i'll print this using printf

statement

so print f bracket inside quotation

sum

is percent d

comma

asterisk result

now let me run this program

as you can see we have computed the sum

of two numbers using the function and

pointers

now to revise what you have learned in

this program here is a programming task

for you create a program to find the

multiplication of two numbers using a

function and a pointer here is how your

programs would work create a function

that assets three pointers inside the

function multiply values represented by

two pointers and assign the result to

the address of the third pointer inside

the main function create three variables

two variables with the value 13 and nine

and third variable to store their

product call the function with addresses

of the three variables as argument store

the return value inside a pointer and

print the value pointed by the returned

address you will find the answer to this

question in our github repository and

also if you want to revise this concept

all these programs will be there as well

i'll put the link in the video

description below now that we have

reached the end of this video it's time

for programming squeeze what type of

value does the following function return

comment your answer below see you in the

next video happy programming

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