WEBVTT 00:00.710 --> 00:06.790 Up until this point we've only ever dealt with the console for input and output. 00:07.760 --> 00:10.100 This doesn't have to be the case though. 00:10.340 --> 00:19.500 We could actually do input and output with files instead to do this will be using the F stream library. 00:19.550 --> 00:21.730 So here's how to use it. 00:21.860 --> 00:37.560 So just clewed F Street K stream of course stands for file stream and this is the standard C++ file 00:37.620 --> 00:39.860 input and output library. 00:40.740 --> 00:44.720 Stream is broken up into O.F. stream for output. 00:45.040 --> 00:49.140 And I have stream for input. 00:49.200 --> 00:57.660 You could also use it as just a stream for both input and output but for this course we'll be using. 00:57.900 --> 01:05.140 We'll be going to use O.F. stream and I have streams separately at least so you can get a feel for things. 01:05.730 --> 01:07.810 Let's see a simple example. 01:07.830 --> 01:11.430 Let's say I wanted to write to a file. 01:11.660 --> 01:16.400 So I'm going to be using O.F. string here. 01:16.500 --> 01:18.510 O f stream. 01:20.260 --> 01:20.780 File 01:24.310 --> 01:27.050 in file. 01:28.960 --> 01:30.330 He will open the file. 01:30.350 --> 01:40.130 So you always have to open a file that you're going to read from or write to. 01:40.940 --> 01:49.960 And in this case this open will actually create the file as long as you write something into it. 01:50.880 --> 01:56.170 So if test that TXI didn't exist it will actually create it. 01:57.320 --> 02:03.800 And we actually use the insertion operator just like we did with C out. 02:03.800 --> 02:16.080 In fact lifestream and IO stream are somewhat closely related so just say hello file. 02:16.090 --> 02:28.010 I know and we can even use an endl for new lines in the file and then once we're done we will close 02:28.010 --> 02:33.020 the file. 02:33.040 --> 02:42.490 So to recap we're making a variable of type O.F. stream live stream is not a structure like we've been 02:42.640 --> 02:44.610 using before. 02:44.680 --> 02:51.940 It's an object which we won't go into in this course just because there's so much to go over with objects 02:53.050 --> 03:02.930 but just know that stream is a type and it's actually again quite similar to see out in many ways the 03:02.930 --> 03:04.080 next line. 03:04.220 --> 03:07.830 We use our out file variable to open a file. 03:07.950 --> 03:08.450 OK. 03:08.510 --> 03:13.970 In this case test DXi DX T. 03:14.420 --> 03:18.680 If it doesn't exist it will be created for you but only if you write to it. 03:18.970 --> 03:21.030 And that's very important. 03:22.160 --> 03:27.400 The next line uses the familiar insertion operator to write to the file. 03:27.420 --> 03:29.940 And again we can even have andle. 03:30.070 --> 03:38.940 And so the last thing we do is close the file and we should always close the file once we're done. 03:39.410 --> 03:45.380 We're done writing to it or reading from it some strange and very bad things could happen if you're 03:45.380 --> 03:47.790 not if you're not doing that. 03:47.920 --> 03:48.860 OK. 03:49.190 --> 03:53.420 So let's run this and see what happens. 03:57.960 --> 04:01.670 So there's no output you'll notice OK. 04:02.100 --> 04:09.290 And we should try to check to see if this test RTX t was written somewhere. 04:09.310 --> 04:12.720 So we go to our directory. 04:12.720 --> 04:17.090 So this is the actual workspace directory for all our projects. 04:17.190 --> 04:19.300 I have a bunch here. 04:20.070 --> 04:26.100 All the ones we've done so far and in file I O which is the current project I'm working on. 04:26.730 --> 04:31.120 You'll see this test XTi. 04:31.470 --> 04:34.810 It's 14 bytes and it's plain text document. 04:35.040 --> 04:44.680 And even in the little preview window you can see it wrote the string that we output to it. 04:44.860 --> 04:47.160 And so you open this 04:51.030 --> 04:56.750 so you'll see the actual string up to it. 04:57.730 --> 05:08.600 So in the next lecture I want to go over how to read this back into our program.