#2: C Variables and Print Output | C Programming for Beginners

00:09:10
https://www.youtube.com/watch?v=h4VBpylsjJc

الملخص

TLDRThis video is part of a series on C programming and focuses on understanding and working with variables. A variable is a named memory location that stores data and can be used later in a program. The video demonstrates how to declare integer variables using the keyword 'int' and provides examples of assigning and changing variable values. It emphasizes using format specifiers like '%d' in 'printf' to print variable contents. Key points include naming variables descriptively, declaring multiple variables at once, and understanding the rules and conventions such as avoiding reserved keywords and not starting variable names with numbers. The video concludes with a quiz to reinforce the concepts learned.

الوجبات الجاهزة

  • 💻 Variables store data in memory for later use.
  • 🔑 Use 'int' to declare integer variables in C.
  • ✅ Assign values directly or separately to variables.
  • 🖨 Use 'printf' and '%d' to print integer variables.
  • 🚫 Avoid using spaces and numbers at the start of variable names.
  • 📝 Descriptive names improve code readability.
  • ↔ Change variable values by reassigning them.
  • 🎓 Understand variable naming rules and conventions.
  • 🔗 Declare multiple variables in one line using commas.
  • 🔍 Some compilers initialize unassigned variables to zero.

الجدول الزمني

  • 00:00:00 - 00:09:10

    The video teaches about variables in C programming, focusing on creating variables and storing data. It starts with defining a variable as a name given to a memory location in computers to store data. The process to create a variable is demonstrated with an example of defining an integer variable using 'int' keyword. The video explains assigning values to a variable and demonstrates merging variable creation and assignment into one line. It details the basic structure of a C program, illustrating with code how to print text and variables using 'printf'. It introduces format specifiers like '%d' for printing integers and shows how changing a variable's value reflects in the output. The example progresses to assigning values of one variable to another and clarifies declaring multiple variables in one line. The video concludes with advice on using descriptive variable names and follows by explaining variable naming rules, emphasizing the importance of camel case for readability. It wraps up by inviting viewers to participate in a quiz on predicting code output.

الخريطة الذهنية

فيديو أسئلة وأجوبة

  • What is a variable in C programming?

    A variable in C is a name given to a memory location where data can be stored and accessed later.

  • How do you declare an integer variable in C?

    You declare an integer variable using the 'int' keyword followed by the variable name, e.g., 'int a;'

  • Can you assign a value to a variable at declaration?

    Yes, you can assign a value during declaration, e.g., 'int a = 25;'

  • How do you change the value of a variable?

    You can change the value by reassigning a new value, e.g., 'a = 31;'.

  • How can variables be printed in C programming?

    Variables can be printed using 'printf' with format specifiers like '%d' for integers.

  • What is a format specifier in C?

    A format specifier tells the 'printf' function what data type to print, e.g., '%d' for integers, '%c' for characters.

  • Can you declare multiple variables in one line?

    Yes, separate them with commas, e.g., 'int a, b;'

  • What happens if you do not assign a value to a variable?

    Its value cannot be determined and may be random or initialized to zero by some compilers.

  • What are the naming rules for variables in C?

    Variable names cannot start with a number, contain spaces, or use reserved keywords.

  • Why should you use descriptive variable names?

    Descriptive names make code easier to understand and maintain.

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التمرير التلقائي:
  • 00:00:00
    hey guys welcome back to this series on
  • 00:00:02
    C programming in this video we will be
  • 00:00:04
    learning about variables more
  • 00:00:06
    specifically we will learn how to create
  • 00:00:08
    variables and store data in them so that
  • 00:00:10
    we can use them later in our program so
  • 00:00:13
    let's get
  • 00:00:17
    started in computer programming a
  • 00:00:20
    variable is a name given to a memory
  • 00:00:22
    location inside our computer where we
  • 00:00:24
    can store data let me give you an
  • 00:00:26
    example I will go to my compiler here
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    you can see int is here the name of the
  • 00:00:31
    variable is is and to create this
  • 00:00:34
    variable we use this keyword int this
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    int keyword is a data type which
  • 00:00:38
    indicates that the a variable can only
  • 00:00:41
    store integer values in C programming
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    every variable must have a type like
  • 00:00:46
    this int we will learn about these data
  • 00:00:48
    types in detail in next video and in
  • 00:00:50
    this video we will continue using int to
  • 00:00:53
    create our variables once we create a
  • 00:00:55
    variable like this in a we can also
  • 00:00:58
    store data into it like is equals to 25
  • 00:01:03
    here we have first created a variable
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    named is and then we have assigned an
  • 00:01:07
    integer value 25 to this a variable by
  • 00:01:11
    the way we have to use this semicolon at
  • 00:01:14
    the end to Mark the end of this
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    statement and it is also possible to
  • 00:01:19
    create variable and assign value in a
  • 00:01:21
    single line let me show you how so
  • 00:01:23
    instead of writing these two lines of
  • 00:01:25
    code we can just merge them and write a
  • 00:01:28
    single line of code like this so I'll
  • 00:01:31
    cut this
  • 00:01:32
    out if you have watched the last video
  • 00:01:35
    we have used a structure that every C
  • 00:01:37
    program follows I'll get back to my
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    compiler if you remember this is the
  • 00:01:42
    basic structure of C program so now
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    let's add a variable inside this main
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    function int is equals to
  • 00:01:54
    25 if we run this code a variable is
  • 00:01:57
    created but we'll not see any output and
  • 00:02:00
    to get output in C programming we will
  • 00:02:03
    use printer function before we print
  • 00:02:06
    this variable let's first try to print a
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    normal text then in the next step we
  • 00:02:10
    will learn to print variables now to
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    print a line of text we use the print
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    function print F bracket inside
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    quotation C
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    programming and we will always end the
  • 00:02:28
    statement with a semicolon
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    now let me run this code and we can see
  • 00:02:34
    C programming is printed on the screen
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    by the way our variable a is also
  • 00:02:39
    created but we haven't seen it because
  • 00:02:41
    we haven't printed it now let's print
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    our variable I just want to print a
  • 00:02:46
    variable so I'll cut this part that
  • 00:02:48
    prints a line of text then I'll write
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    print F bracket inside
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    quotation percent D comma and the name
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    of the variable in this case the name of
  • 00:03:00
    the variable is is to print a variable
  • 00:03:03
    in C programming we use something called
  • 00:03:06
    format specifier here person D is a
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    format
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    specifier now let's run this
  • 00:03:14
    code as we can see 25 is printed as an
  • 00:03:18
    output so what happens here is that here
  • 00:03:22
    person D is replaced by the value of a
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    variable if we have to print other data
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    like characters and decimals we use
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    different specifier like percent C and
  • 00:03:31
    percent F which we will discuss in the
  • 00:03:34
    next video let me modify this program a
  • 00:03:37
    bit here I'll write
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    here is colon now let me run this code
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    again now we can see this a column is
  • 00:03:48
    printed as it is and person D is
  • 00:03:50
    replaced with the value of
  • 00:03:55
    a now that we know how to store data in
  • 00:03:58
    variables let's see see how we can
  • 00:04:00
    change their values yes we can change
  • 00:04:02
    the values of variable that's why it is
  • 00:04:05
    called variable let me give you an
  • 00:04:07
    example I'll go back to my previous
  • 00:04:09
    example currently the a variable stores
  • 00:04:12
    25 now I'll assign a new value to this a
  • 00:04:16
    variable a is equal to 31 and I'll print
  • 00:04:23
    this new is
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    semicolon percent D and and comma and
  • 00:04:31
    again a and end this with semicolon
  • 00:04:34
    let's run this
  • 00:04:35
    program as you can see initially the
  • 00:04:38
    value of a was 25 then I changed the
  • 00:04:40
    value of a by assigning 31 now let me
  • 00:04:43
    put this second line of code into a new
  • 00:04:46
    line for that I'll use back sln and I'll
  • 00:04:50
    run this again and you can see the
  • 00:04:52
    output it is more readable and more
  • 00:04:55
    clearer so here this back sln is a new
  • 00:04:58
    line character simply speaking it is a
  • 00:05:01
    inter
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    key so far we saw that we can assign
  • 00:05:06
    data directly to a variable however we
  • 00:05:09
    can also assign a value of one variable
  • 00:05:11
    to another let me show you an example in
  • 00:05:14
    this example as you can see we have
  • 00:05:16
    assigned value 33 to this first number
  • 00:05:19
    variable and we have then printed this
  • 00:05:21
    first number variable now I'll assign
  • 00:05:24
    another variable second number
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    and instead of assigning any data I'll
  • 00:05:33
    assign here first
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    number then I'll print
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    this back sln so that we can get a
  • 00:05:44
    readable
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    output second
  • 00:05:48
    number equals to perc
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    D and name of the variable that is
  • 00:05:54
    second
  • 00:05:57
    number now let's see what will happen
  • 00:06:00
    I'll run this
  • 00:06:02
    code and we can see first number and
  • 00:06:05
    second number variable holds the same
  • 00:06:07
    value 33 let's see how this program
  • 00:06:10
    works line by line first we have created
  • 00:06:12
    this variable first number and assigned
  • 00:06:15
    value 33 to it then we have printed this
  • 00:06:18
    variable and then we assigned another
  • 00:06:21
    variable second number and assigned the
  • 00:06:23
    value of the first number to it then we
  • 00:06:25
    have printed the second number
  • 00:06:31
    we can also declare multiple variables
  • 00:06:33
    in a single line let me give you an
  • 00:06:35
    example here I have created two
  • 00:06:37
    variables variable one and variable two
  • 00:06:40
    and I have separated them with the comma
  • 00:06:42
    in a single line let me modify this
  • 00:06:45
    program a bit I'll assign a value 25 to
  • 00:06:48
    this variable too here the same two
  • 00:06:50
    variables are created however the value
  • 00:06:53
    of variable 2 is now 25 by the way in C
  • 00:06:57
    programming if we do not assign a value
  • 00:06:59
    to a variable its value cannot be
  • 00:07:01
    determined in this program variable one
  • 00:07:03
    will have some random unpredictable
  • 00:07:05
    value however some compilers may store
  • 00:07:08
    Jero in them okay guys we need your
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    support to keep this type of content
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    free for all users YouTube really likes
  • 00:07:16
    engagement on the video so leave a
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    comment below press that like button and
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    hit subscribe if you haven't already
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    let's get the engagement score high up
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    so that more people can discover and
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    enjoy these courses
  • 00:07:31
    at this point we have covered all the
  • 00:07:33
    basics of variable before ending this
  • 00:07:35
    video let's talk about how to choose a
  • 00:07:37
    good variable name if you have noticed I
  • 00:07:40
    have used descriptive variable names
  • 00:07:42
    like a and first number we could have
  • 00:07:44
    given variable names like a instead of
  • 00:07:47
    A's and FN instead of first number it
  • 00:07:50
    works just fine however it's hard to
  • 00:07:53
    understand what a means just by looking
  • 00:07:55
    at the code so when we use good
  • 00:07:58
    descriptive variable names it becomes
  • 00:08:00
    easier to understand the code and to
  • 00:08:02
    make the variable name descriptive we
  • 00:08:05
    may need to use names having more than
  • 00:08:07
    one word in such cases we follow the
  • 00:08:09
    camel case format while giving the names
  • 00:08:11
    to the variable in camel case the first
  • 00:08:14
    word will be of small letter and the
  • 00:08:16
    first letter of the second word will be
  • 00:08:18
    of capital letter like the example shown
  • 00:08:20
    on the screen by the way there are some
  • 00:08:23
    rules you need to know while creating a
  • 00:08:25
    variable you cannot create variable
  • 00:08:27
    names with space in between you cannot
  • 00:08:30
    start variable names with numbers and
  • 00:08:33
    you cannot use certain words as variable
  • 00:08:35
    names you cannot use if as a variable
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    name because if is a keyword these
  • 00:08:40
    keywords are part of C programming
  • 00:08:42
    syntax and have special meaning in C we
  • 00:08:45
    will learn about these keywords as we
  • 00:08:47
    progress through the course and now we
  • 00:08:49
    are at the end of this video it's time
  • 00:08:52
    for programing quiz can you guess the
  • 00:08:54
    output of this program comment your
  • 00:08:57
    answer below and I'll see you in the
  • 00:08:59
    next video video Happy programming
  • 00:09:04
    [Music]
الوسوم
  • C Programming
  • Variables
  • Data Types
  • Integer
  • Assignment
  • Print Function
  • Format Specifier
  • Naming Conventions
  • Compiler