WEBVTT 0 00:01.920 --> 00:06.300 et us see conditional statements if is a conditional statement 1 00:09.300 --> 00:14.370 here I should mention the condition if the condition is true then this block will be executed. 2 00:14.640 --> 00:21.510 I will write C out Hello new line. 3 00:21.660 --> 00:29.610 Now I must mention a conditional statement here he is giving an error message that expected expression. 4 00:29.640 --> 00:34.230 So I will the write one let us see what happens. 5 00:34.240 --> 00:35.990 I run the program. 6 00:36.210 --> 00:36.630 Hello. 7 00:36.630 --> 00:38.270 Is displayed here. 8 00:38.880 --> 00:44.320 If I write as 0 . 9 00:44.370 --> 00:53.030 It is false see here I got a warning that code will never be executed. 10 00:53.820 --> 00:59.830 Silence by adding parentheses to mark code as explicitly dead. 11 01:00.390 --> 01:09.300 But still I will run because this is the warning program will compile and run. 12 01:09.370 --> 01:14.500 It's working and has displayed hello It means minus 10 is taken as true. 13 01:15.160 --> 01:17.880 I can use this keyword true also. 14 01:18.370 --> 01:19.190 Now let us. 15 01:19.270 --> 01:21.250 add else block to this one 16 01:25.230 --> 01:25.880 here. 17 01:25.910 --> 01:29.430 I will display a message cout bye 18 01:33.480 --> 01:36.630 endl let us run this and see 19 01:39.750 --> 01:45.660 only hello is displayed and here I am getting a warning that this code is not reachable, never executed 20 01:45.690 --> 01:48.850 because I have mentioned true here so always it will enter in. 21 01:48.900 --> 01:53.940 If block it will not enter into else block and instead of true. 22 01:53.940 --> 02:00.840 If I write false here then still I get a warning that this blog will not be executed at all. 23 02:00.840 --> 02:05.710 This block will be executed any way I can run and see what happens. 24 02:05.730 --> 02:07.730 It will go in the else block and display. 25 02:07.740 --> 02:08.490 Bye. 26 02:08.670 --> 02:18.060 Yeah it is displaying bye here so I can use constant values like 0 or 1 or any other number for true 27 02:18.390 --> 02:22.250 or I can write keywords like true or false. 28 02:24.730 --> 02:29.580 Let us write a program to take the roll number from the keyboard and check whether that number is valid 29 02:29.580 --> 02:30.110 or not. 30 02:30.210 --> 02:35.880 So for that I will declare a variable called Roll and cout 31 02:36.870 --> 02:40.320 enter your roll number 32 02:44.330 --> 02:49.740 cin roll 33 02:49.770 --> 02:58.280 Here we check if rule number is less than 1 number cannot be zero. 34 02:58.280 --> 03:02.000 Mostly all numbers start from 1 only if it is less than 1. 35 03:02.090 --> 03:09.410 Then we will say say cout invalid roll number 36 03:13.840 --> 03:25.920 else cout valid roll no. 37 03:26.360 --> 03:30.530 So the common thing found mostly in like on any Web site. 38 03:30.530 --> 03:32.670 If you are registering they us ask for email. 39 03:32.870 --> 03:35.330 They will check whether your email is right or not. 40 03:35.490 --> 03:37.160 they will ask age or date of birth. 41 03:37.160 --> 03:43.660 But if you enter a future date then they will say it will give a message that your data is invalid 42 03:44.570 --> 03:46.430 so that the called as validation. 43 03:46.430 --> 03:48.260 So this is like a validation code. 44 03:48.260 --> 03:52.890 So after taking a roll no. i am just checking weather the roll number is valid or not. 45 03:52.910 --> 03:59.510 So roll no. cannot be less than 1 so that's what I am checking if it is less than onc say a valid otherwise 46 03:59.510 --> 04:02.390 valid Let's run and see the program 47 04:06.470 --> 04:10.370 enter your roll number minus one invalid number. 48 04:10.370 --> 04:12.950 Here is a message invalid roll no. 49 04:18.040 --> 04:21.280 two enter, valid roll no. 50 04:22.210 --> 04:26.070 There's a valid number that's it. 51 04:26.110 --> 04:29.740 So you can try this program on your computer. 52 04:30.750 --> 04:33.820 I suggest you do try this program by yourself.