1
00:00:05,500 --> 00:00:08,900
In this video, we'll write some code that will allow us to create some files,

2
00:00:08,900 --> 00:00:11,100
and we'll create some files a couple of different ways.

3
00:00:11,100 --> 00:00:14,300
First, we'll create a real simple file just write a string to it.

4
00:00:14,300 --> 00:00:19,100
And then what we'll do is we'll write a couple of copy file utilities, just like we did in the slides.

5
00:00:20,660 --> 00:00:25,360
Okay. So I'm in the section 19 workspace in the write file project.

6
00:00:25,720 --> 00:00:29,420
And I've got nothing going on here except these includes. I'm including iostream,

7
00:00:29,420 --> 00:00:30,920
fstream and string.

8
00:00:31,470 --> 00:00:34,170
Let's get started. First thing we need to do is let's create an

9
00:00:34,170 --> 00:00:37,370
ofstream object. So we'll call it std ofstream,

10
00:00:38,520 --> 00:00:42,720
and we'll call it out file since it's going to be an output file,

11
00:00:42,720 --> 00:00:46,520
and we'll initialize it to dot dot slash, again, I'm in CodeLite that's why I'm

12
00:00:46,520 --> 00:00:50,520
doing this, and I'll name the file output.txt.

13
00:00:53,520 --> 00:00:57,180
Okay. Now we'll check to see that it was opened correctly.

14
00:00:57,180 --> 00:00:58,680
So if not out file,

15
00:00:59,780 --> 00:01:03,140
then what we're going to say is just get out of here, right, some error.

16
00:01:04,129 --> 00:01:08,130
So we'll provide an error, saying error creating file

17
00:01:09,900 --> 00:01:11,400
because it is an output file.

18
00:01:13,760 --> 00:01:16,010
And we'll return something other than 0.

19
00:01:17,780 --> 00:01:21,280
Let me get rid of that extra quote right here, and we'll return one.

20
00:01:22,980 --> 00:01:27,230
That's it so if we get now to this line 13, we know our file has been

21
00:01:27,230 --> 00:01:30,590
created in this case. Remember, if the file does not exist,

22
00:01:30,590 --> 00:01:34,390
it's going to be created. Right now it does not exist, so it will be created.

23
00:01:34,590 --> 00:01:38,740
If it does exist, it'll be truncated. Okay. So we'll lose whatever was in there before.

24
00:01:38,740 --> 00:01:40,400
So let's create a string variable.

25
00:01:41,060 --> 00:01:43,420
We'll just call it line,

26
00:01:44,300 --> 00:01:48,180
and we'll ask the user we can call that variable name anything we want.

27
00:01:48,180 --> 00:01:50,680
We'll ask the user to enter something

28
00:01:51,340 --> 00:01:52,940
to write to the file.

29
00:01:55,600 --> 00:01:57,600
And we'll simply read it from --

30
00:01:59,100 --> 00:02:03,090
we'll use getline to read it because we want to read more than just one word. So we'll say getline

31
00:02:03,590 --> 00:02:05,790
from cin into line.

32
00:02:07,790 --> 00:02:08,789
Remember, again,

33
00:02:09,690 --> 00:02:13,890
we're using string objects here, we're not using c-style strings.

34
00:02:14,890 --> 00:02:17,590
That's it. So what do we do now. We say out file,

35
00:02:19,590 --> 00:02:23,390
and we insert that line into that file,

36
00:02:23,390 --> 00:02:27,380
and we'll give it a new line as well. Remember, endline will flush out the buffer,

37
00:02:27,740 --> 00:02:30,240
and then we're done here we'll just close the file.

38
00:02:32,600 --> 00:02:35,200
That's it, pretty easy. Now if we run this,

39
00:02:35,860 --> 00:02:36,850
let's do that.

40
00:02:39,350 --> 00:02:41,710
Enter something to write to the file, I'm going to say hello

41
00:02:43,210 --> 00:02:47,210
there file, I'll press enter, program is done.

42
00:02:47,210 --> 00:02:51,200
I'll exit this. Now there is nothing that shows up here by default.

43
00:02:51,200 --> 00:02:54,000
Some of the IDEs will show that file when it's created,

44
00:02:54,000 --> 00:02:57,500
CodeLite doesn't. So what you can do is you can select the project

45
00:02:57,500 --> 00:03:00,800
right click and say open containing folder,

46
00:03:01,300 --> 00:03:04,660
that'll open it up in explorer or in finder if you're on a mac.

47
00:03:05,100 --> 00:03:07,100
And I'll just drag that over here.

48
00:03:07,100 --> 00:03:12,090
And you can see that's right here we just created the file name. Remember -- let me drag this down just a little bit.

49
00:03:12,090 --> 00:03:16,090
The file name was output.txt. There's output.txt right here.

50
00:03:16,490 --> 00:03:19,490
And you can see the contents of it right over here hello there file.

51
00:03:20,850 --> 00:03:23,850
Okay. Now let me move this out of the way, and let's run this again.

52
00:03:24,510 --> 00:03:26,010
And if we run it again,

53
00:03:27,210 --> 00:03:29,210
I'll just say my name is Frank

54
00:03:30,460 --> 00:03:31,560
and press enter.

55
00:03:32,660 --> 00:03:35,460
And now if we look at the file again, I'll drag this back over.

56
00:03:35,460 --> 00:03:38,860
You can see that what was there before was erased

57
00:03:38,860 --> 00:03:42,960
because we're opening the file in truncation mode so it gets rid of whatever was there.

58
00:03:42,960 --> 00:03:46,320
That's the default. Now if we want to add something to the file,

59
00:03:46,320 --> 00:03:50,520
we can simply open it in the pen mode. So we can put a another flag here and just say --

60
00:03:50,880 --> 00:03:55,870
we'll say std ios append mode or app.

61
00:03:56,120 --> 00:03:59,720
And if we run this again now, we say this

62
00:03:59,720 --> 00:04:01,920
should be another line.

63
00:04:03,420 --> 00:04:05,780
Okay. So we'll take a look at the file now.

64
00:04:06,180 --> 00:04:09,680
And you can see my name is Frank, and now I put this should be another line.

65
00:04:10,180 --> 00:04:13,380
Okay. So you can see that it's actually appending to the existing file.

66
00:04:13,380 --> 00:04:16,380
So that's it. That's pretty straightforward and really that's the basics

67
00:04:16,380 --> 00:04:18,880
of output to text files.

68
00:04:18,880 --> 00:04:21,680
We have the power of all those stream manipulators,

69
00:04:21,680 --> 00:04:25,040
which really gives us a lot of power into how we format the output files.

70
00:04:25,040 --> 00:04:28,040
Okay. So what I want to do now is I want to switch to

71
00:04:28,590 --> 00:04:29,470
another project.

72
00:04:29,470 --> 00:04:34,270
It's going to be the CopyFile_1 project. So I'll switch to that, and I'll be right back.

73
00:04:36,070 --> 00:04:38,370
Okay. So I'm in the section 19 workspace.

74
00:04:38,370 --> 00:04:41,470
And I've opened up now the CopyFile_1 project.

75
00:04:41,470 --> 00:04:44,770
And in this project, what we've got is this poem. We've got

76
00:04:44,770 --> 00:04:49,030
Shakespeare's sonnet again. And what we want to do is we just want to copy it to another file.

77
00:04:49,030 --> 00:04:53,030
So what we can do is I've already written the code, and it's really really straightforward.

78
00:04:53,030 --> 00:04:56,930
It's just like it was in the slides. What we can do is we can start here.

79
00:04:56,930 --> 00:04:59,280
And you can see we've got our includes that we need,

80
00:04:59,280 --> 00:05:03,280
and we've got an input file stream called infile, which is my poem.

81
00:05:03,580 --> 00:05:06,460
And then I've got an output file stream called out file,

82
00:05:06,460 --> 00:05:11,120
which is my poem_out.txt that's the file we want to create

83
00:05:11,120 --> 00:05:14,120
that's going to be a copy of the poem.txt file.

84
00:05:15,670 --> 00:05:20,550
So again, we're basically following the recipe. We're instantiating those objects.We're making sure that

85
00:05:20,550 --> 00:05:23,750
our file streams are open and ready to read and write.

86
00:05:23,750 --> 00:05:28,110
And then we've got our logic. And our logic is really only just a couple of lines of code.

87
00:05:28,110 --> 00:05:33,010
We've got a line that we want to read file -- the file input into, and there's my loop.

88
00:05:33,450 --> 00:05:36,750
I'm using getline to read a line from infile.

89
00:05:37,550 --> 00:05:41,210
And when I get that line, all I'm going to do is write it to out file. That's it.

90
00:05:41,210 --> 00:05:44,510
At the end, we're going to display a little message that says file copied.

91
00:05:44,510 --> 00:05:47,810
And we're going to close both files. So if we run this,

92
00:05:49,410 --> 00:05:54,180
it'll say file copied. That's it. You can see how quickly this runs.

93
00:05:54,730 --> 00:05:59,090
And we'll open up that project, the containing folder. And we should see

94
00:05:59,090 --> 00:06:00,560
a poem underscore out.

95
00:06:00,560 --> 00:06:04,320
There it is right here that was just created 1k big.

96
00:06:04,320 --> 00:06:07,920
And if I select it, you can see that the poem is over here.

97
00:06:07,920 --> 00:06:12,120
This is the original poem, and this is the copied poem. So it's exactly the same.

98
00:06:12,120 --> 00:06:14,620
So it's really easy to copy one file to another.

99
00:06:14,620 --> 00:06:19,120
In this case, we used formatted input and output because we're using getline,

100
00:06:19,780 --> 00:06:23,340
and we're using the insertion operator with line to write it to the file.

101
00:06:23,340 --> 00:06:27,640
That's it. Now if we go over to CopyFile_2 project,

102
00:06:27,640 --> 00:06:28,640
let me open that up.

103
00:06:31,300 --> 00:06:36,180
It's exactly the same thing. The only difference here is that we're using get and put. . So we're using

104
00:06:36,180 --> 00:06:37,880
unformatted input output.

105
00:06:37,880 --> 00:06:42,130
And you can see that the code is exactly the same except the while loop and the

106
00:06:42,130 --> 00:06:47,030
variable declaration right there. That's the only difference is we're doing it one character at a time.

107
00:06:47,030 --> 00:06:50,020
So while we get a character from infile,

108
00:06:50,020 --> 00:06:53,020
we output that character to outfile. That's it.

109
00:06:53,270 --> 00:06:57,170
So let's run this. I'll select that, make sure that that project is selected.

110
00:06:57,570 --> 00:07:00,070
I'll run this. It's done.

111
00:07:00,470 --> 00:07:03,970
And I'll open up that project in the containing folder.

112
00:07:04,960 --> 00:07:07,220
And right here, you'll see poem.out.

113
00:07:08,100 --> 00:07:10,900
And it's right over here, you can see it right there.

114
00:07:12,780 --> 00:07:17,440
So that's it for this video. Here you can see a few examples of creating files,

115
00:07:17,690 --> 00:07:21,190
appending to files and copying files using unformatted and formatted io.

116
00:07:21,690 --> 00:07:25,690
Next is a challenge. And in the challenge what we're going to do is we're going to take

117
00:07:25,690 --> 00:07:30,190
Shakespeare's, Romeo and Juliet and add line numbers to it and create a new file.

118
00:07:30,550 --> 00:07:31,550
I'll see you there.