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← C Programming Tutorial - 15 - Simple Array Program

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Showing Revision 3 created 12/05/2019 by jmmartin.

  1. What's up, everyone? Welcome to
    your—uh, it's like, 15th or somethin'—
  2. tutorial on arrays. And the
    last one was on arrays,
  3. but I promised that I would build
    an application to show you guys
  4. why arrays are actually useful,
    so that's what I'm going to do now.
  5. So, all you have to do is follow along,
    and open your mind, and... just learn.
  6. The first thing that I'm gonna do
    is build an array, just like last time.
  7. Let's put five elements in it.
  8. And let's go ahead and fill this
    array with some kind of elements.
  9. Let's say, the ages of...
    my brothers and sisters.
  10. And... I don't have five
    brothers and sisters, so...
  11. We'll go 21 for me, 18, uh... let's say,
    pretend I had one that was 47.
  12. Another one that was 21.
    That's my twin, named Mucky.
  13. And another baby sister named 4.
  14. So that's one, two, three, four, five.
  15. So remember, the position
    number for each of these
  16. is zero, one, two, three, four.
  17. And you could have these any
    numbers you want; it doesn't matter.
  18. The next thing I'm gonna do is go
    ahead and build a counting variable.
  19. And in case you guys don't know—and
    by "case," I mean you guys don't know,
  20. because I didn't tell you yet.
  21. This application is just gonna add
    up all the numbers in the array for us.
  22. So, we're gonna be building a
    "for" loop later with a counting variable,
  23. so that's why I need that.
  24. And the last thing I need is a variable
    to keep the sum of the total,
  25. or, pretty much, the sum or
    the total; however you say it.
  26. So now that we got our
    array in two variables,
  27. one for the counting variable
    and one to keep the sum,
  28. let's go ahead and build a for loop.
  29. Now, our first condition is,
    I need to start at zero.
  30. And this is because the
    first position number of this,
  31. is gonna be zero,
    and it's gonna go to four.
  32. So let's go ahead and add our
    next condition, the maximum.
  33. "i" is less than five.
  34. And we have less than five
    and not equal to five because
  35. it's always gonna be
    less than five, which is four.
  36. If we put less than or equal to,
    it's gonna try to get that fifth number,
  37. and zero, one, two, three, four—
  38. there is no five; it always
    goes from zero to four.
  39. Not always, but in this case.
  40. And now, let's go ahead.
  41. Since we wanna just loop
    it through one at a time.
  42. Don't get anything fancy.
  43. So, let me go ahead and—
    Come on. Format.
  44. Whatever. Do this the hard way.
  45. So... Wow, this is a pain
    in the butt right now.
  46. So, next, we have to write
    what we want our program to do.
  47. So let's go ahead and take the total.
  48. And right now, the total is zero.
  49. So what we wanna
    add to it is, loop through.
  50. Let me—let me type. I can't, uh,
    think and type at the same time.
  51. And that is our program right there.
  52. So, what this is gonna do
    is it's gonna go, all right.
  53. You now have the variable i=0.
  54. So we're gonna take the zeroth-
    position number, which is 21,
  55. and add it to the total.
  56. Next, we're gonna loop through
    when i equals one.
  57. So when i equals one, we're gonna
    take 18, and add it to the total.
  58. So whatever 18 +21 is,
    and that's gonna be the total.
  59. Next, it's just gonna
    loop through all of that
  60. until we get through
    all of these, right here.
  61. So, just to output something on the screen
    to prove to you guys that it worked.
  62. Go ahead and printf.
  63. Did I get that right? Yep.
  64. Uh... let's go ahead... how
    are we gonna format this?
  65. "The total number is..." And I know
    I'm spelling everything wrong.
  66. I know I spelled "number" wrong, so don't
    comment a thousand times tellin' me.
  67. "%d." Let's go ahead
    and add a new line.
  68. No, we won't. Just kiddin', sucker.
  69. "total." So, let me just run this real
    quick, and then I'll explain to you guys
  70. exactly what it did one last time, so
    you guys aren't totally lost in the dark.
  71. So it's gonna loop through, and it's
    gonna say the total number is—
  72. again, "numebr," is 111.
    That's exactly what we wanted.
  73. Now, one last time, let me explain
    to you guys how, exactly, this worked.
  74. The first thing we did is build
    an array with five elements in it.
  75. Now, those arrays are listed
    zero through four,
  76. just 'cause your computer's weird.
  77. Next thing we do is go to
    a counting variable,
  78. and build a variable to hold
    the sum of our numbers.
  79. We started with a zero-with
    element in our array,
  80. and looped through until
    we got to number four.
  81. As you can say, "i" is less
    than 5, which is 4.
  82. And this is just the
    loop-through one at a time.
  83. We then took each of those elements
    and added it into the total variable,
  84. so it looped through each time,
    and each time it did,
  85. it added a new number
    to the variable total.
  86. And at the end—you guys
    should know this by now.
  87. What we did is simply
    print out that number.
  88. So again, that is one way that you
    can use a loop to loop through
  89. the elements in your array,
    and this is just to show you guys
  90. that array isn't totally useless, and
    you can actually use it for something.
  91. So, this is a very simple program.
    I encourage you guys to build this.
  92. Again, I wanna thank
    you guys for watching.
  93. Don't forget to subscribe to my channel.
  94. Again, thank you, and make sure
    to check out my next tutorial.