1 00:00:01,060 --> 00:00:07,420 Programming often involves examining a set of conditions and deciding which action to take based on 2 00:00:07,420 --> 00:00:08,440 these conditions. 3 00:00:08,470 --> 00:00:15,580 Python's If statement allows you to examine the current state of a program and respond appropriately 4 00:00:15,580 --> 00:00:16,510 to that state. 5 00:00:16,540 --> 00:00:22,660 In this section, you will learn to write conditional tests which allow you to check any condition of 6 00:00:22,660 --> 00:00:27,970 interest, and you will learn to write simple if statements and you will learn how to create a more 7 00:00:27,970 --> 00:00:35,320 complex series of if statements to identify when the exact conditions you want are present, and you 8 00:00:35,320 --> 00:00:41,410 will then apply this concept to lists and so you will be able to write a for loop that handles most 9 00:00:41,410 --> 00:00:47,070 items in a list one way, but handles certain items in a with specific values in different way. 10 00:00:47,080 --> 00:00:57,440 So this example here we will show the if tests that let you respond to special situations correctly. 11 00:00:57,460 --> 00:01:02,810 Imagine you have a list of cars and you want to print out the name of each car. 12 00:01:02,810 --> 00:01:04,910 So car names are proper names. 13 00:01:04,910 --> 00:01:09,440 So the names of most cars will be printed in title names title case. 14 00:01:09,470 --> 00:01:16,160 However, the value BMW here should be printed in all uppercase and here we will. 15 00:01:16,160 --> 00:01:17,900 Which we will do that right now. 16 00:01:17,900 --> 00:01:23,120 So we will car makers, car makers here. 17 00:01:23,120 --> 00:01:25,130 And after that we will equal to. 18 00:01:25,160 --> 00:01:33,680 So first we will enter the Volkswagen, the BMW, the Toyota, Toyota. 19 00:01:37,020 --> 00:01:37,710 Port. 20 00:01:38,650 --> 00:01:39,430 And. 21 00:01:41,760 --> 00:01:49,740 And here we will use the four car in car makers and here. 22 00:01:49,740 --> 00:02:02,430 So if car equals to BMW, then we will print the car dot upper and else here we will. 23 00:02:02,460 --> 00:02:07,650 Else we will print the car dot title. 24 00:02:07,650 --> 00:02:08,550 That's it. 25 00:02:08,550 --> 00:02:10,500 So now let's run it. 26 00:02:10,890 --> 00:02:11,460 That's it. 27 00:02:11,460 --> 00:02:12,090 Here. 28 00:02:12,360 --> 00:02:12,680 Oops. 29 00:02:13,050 --> 00:02:17,820 If BMW oops if BMW, that's it. 30 00:02:18,180 --> 00:02:20,130 Now this will work here. 31 00:02:21,450 --> 00:02:24,240 So now the loop in this example. 32 00:02:24,240 --> 00:02:25,260 First checks. 33 00:02:25,260 --> 00:02:32,460 If the current value of a car, if the current value of a car is BMW. 34 00:02:33,760 --> 00:02:39,440 If it is, the value is printed in uppercase here with this function. 35 00:02:39,460 --> 00:02:40,030 Right. 36 00:02:40,300 --> 00:02:47,050 If the value of a car is anything other than a BMW, it is printed in a title case. 37 00:02:47,170 --> 00:02:49,840 And here this is our output here. 38 00:02:50,020 --> 00:02:58,000 All of these names are written in title case, but here BMW is written in uppercase. 39 00:02:58,000 --> 00:03:02,730 So this example combines the number of concepts you will learn about in this section. 40 00:03:02,740 --> 00:03:09,220 Let's begin by looking at the kinds of tests you can use to examine the conditions in your program, 41 00:03:09,220 --> 00:03:12,850 so we can also use conditional tests in Python. 42 00:03:12,850 --> 00:03:18,820 So at the heart of every if statement is an expression that can be evaluated as true. 43 00:03:19,060 --> 00:03:20,800 As true. 44 00:03:22,630 --> 00:03:24,460 Or false, Right? 45 00:03:29,990 --> 00:03:41,630 So Python uses the values true and false to decide to decide whether the code is in a if statement should 46 00:03:41,630 --> 00:03:42,950 be executed or not. 47 00:03:42,980 --> 00:03:46,550 So if a conditional test evaluates true. 48 00:03:47,470 --> 00:03:52,240 Then Python executes the code following the if statement. 49 00:03:52,240 --> 00:03:54,550 So if the test evaluates false. 50 00:03:54,910 --> 00:03:58,540 If python ignores the code following the if statement. 51 00:03:58,930 --> 00:04:00,490 We can also check for equality. 52 00:04:00,490 --> 00:04:06,130 So the most conditional test compare the current value of a variable to a specific value of interest. 53 00:04:06,130 --> 00:04:13,990 So the simplest conditional test check test checks whether the value of a variable is equal to the value 54 00:04:13,990 --> 00:04:14,860 of interest. 55 00:04:14,890 --> 00:04:20,350 In order to do that, we will just delete for now our for loop and we will print here. 56 00:04:20,740 --> 00:04:25,870 Now car equals BMW here. 57 00:04:26,050 --> 00:04:31,120 Or let's actually, instead of writing that, let's use car makers. 58 00:04:31,120 --> 00:04:36,370 BMW index is one BMW and BMW here. 59 00:04:36,610 --> 00:04:41,740 So now as you can see we got an error cannot assign to a function call. 60 00:04:41,740 --> 00:04:46,480 So here that is we're going to get an error if we try to do that. 61 00:04:46,480 --> 00:04:50,960 However, if you try this in Python console, which we will now. 62 00:04:52,850 --> 00:04:53,270 Here. 63 00:04:53,270 --> 00:04:54,650 We opened our python. 64 00:04:54,650 --> 00:04:59,090 Now you can reach this by using just python. 65 00:05:00,900 --> 00:05:05,070 And here you're going to see this python 64 bit or 32 bit. 66 00:05:05,100 --> 00:05:09,450 You just enter that and here you can see the new tab opened. 67 00:05:09,480 --> 00:05:12,050 Here, let's actually make it closer. 68 00:05:12,060 --> 00:05:13,290 So most conditional. 69 00:05:13,290 --> 00:05:17,940 Let's ah, compare the current value of a variable to a specific value of interest. 70 00:05:17,970 --> 00:05:22,170 Let's create a new value named car here and make it BMW. 71 00:05:22,410 --> 00:05:26,850 And after that we will check the is car equal to BMW. 72 00:05:26,880 --> 00:05:30,730 And here you can you can see we got true. 73 00:05:30,750 --> 00:05:34,530 So the first line here actually, let me get this. 74 00:05:34,530 --> 00:05:38,010 So this first line, let me fix this. 75 00:05:38,040 --> 00:05:41,190 Now here, this first line here. 76 00:05:42,330 --> 00:05:44,250 Sets the value of a car. 77 00:05:44,890 --> 00:05:51,880 Car sets the value of a car to be actual b m. 78 00:05:51,880 --> 00:05:52,840 W. 79 00:05:54,320 --> 00:05:56,720 Using a single equal sign. 80 00:05:56,720 --> 00:06:00,860 So here we use the single equal sign here. 81 00:06:00,860 --> 00:06:01,460 Right? 82 00:06:02,860 --> 00:06:05,770 As you've seen many times already, this sign. 83 00:06:05,770 --> 00:06:12,460 So the next line checks the whether the value of a cars is BMW. 84 00:06:12,490 --> 00:06:14,590 Here you see here. 85 00:06:16,000 --> 00:06:16,950 Of sexual issues. 86 00:06:16,960 --> 00:06:18,310 Different color here. 87 00:06:21,540 --> 00:06:27,630 So now we are checking this by using a double equal sign. 88 00:06:28,170 --> 00:06:30,360 Double equal sign. 89 00:06:32,120 --> 00:06:32,660 Here. 90 00:06:33,020 --> 00:06:34,010 Car. 91 00:06:35,450 --> 00:06:36,280 Is. 92 00:06:37,700 --> 00:06:38,540 We? 93 00:06:39,440 --> 00:06:40,940 And W. 94 00:06:42,150 --> 00:06:46,830 So this is the equality operator. 95 00:06:46,950 --> 00:06:54,090 So and so this equality operator here, this is this is named equality Operator. 96 00:06:54,090 --> 00:06:57,150 Let me actually write that here. 97 00:06:57,180 --> 00:06:59,880 This is equality. 98 00:07:06,160 --> 00:07:07,120 Operator. 99 00:07:12,950 --> 00:07:18,710 So here this equality operator returns true, like in this case. 100 00:07:19,780 --> 00:07:25,030 If the values on the left and the right side of the operator match in this case, these are match. 101 00:07:25,030 --> 00:07:28,420 So car is actually equals to BMW. 102 00:07:28,450 --> 00:07:30,400 Actually, let me use the different color. 103 00:07:30,400 --> 00:07:35,500 So here our car is equals to BMW here. 104 00:07:36,480 --> 00:07:39,240 Because we already assign that in first line. 105 00:07:39,240 --> 00:07:43,410 And our BMW here equals to BMW, Right. 106 00:07:43,800 --> 00:07:52,500 So we are checking this BMW W and here they match. 107 00:07:52,530 --> 00:07:55,710 In this case, they will return. 108 00:07:55,740 --> 00:07:56,490 True. 109 00:07:58,310 --> 00:07:59,150 That's it. 110 00:07:59,570 --> 00:08:02,600 But here the values in this example. 111 00:08:02,600 --> 00:08:03,500 Match. 112 00:08:03,500 --> 00:08:04,160 Match. 113 00:08:04,160 --> 00:08:06,830 So Python returns true. 114 00:08:07,130 --> 00:08:15,380 So when the value of a car is anything other than a BMW, for example, let's try car equals equal the 115 00:08:15,620 --> 00:08:27,590 jeep here we will get false if car equal equal uppercase B M-W We will get false again because these 116 00:08:27,590 --> 00:08:34,580 equations equalization equation equality operator are case sensitive in strings. 117 00:08:34,580 --> 00:08:42,830 So here if we try something ice cream, ice cream, we will get false again. 118 00:08:43,450 --> 00:08:44,290 So. 119 00:08:45,450 --> 00:08:47,910 That's it here with operator. 120 00:08:47,910 --> 00:08:51,150 So a single equal sign is really a statement. 121 00:08:51,150 --> 00:08:58,410 And you might read the first line of a code here that we are setting a set the value of a car equal 122 00:08:58,410 --> 00:08:59,010 to. 123 00:09:00,440 --> 00:09:00,670 It. 124 00:09:00,860 --> 00:09:07,100 For example, Jeep, on the other hand, a double equal sign ask asks a question. 125 00:09:07,100 --> 00:09:08,900 Let me actually write it down. 126 00:09:09,200 --> 00:09:13,760 Some new programmers might confuse this with equate initialization. 127 00:09:14,970 --> 00:09:15,560 Here. 128 00:09:15,570 --> 00:09:19,530 So this this double equal. 129 00:09:19,740 --> 00:09:23,970 Double equal signs asks the Or. 130 00:09:27,830 --> 00:09:30,200 Here asks this. 131 00:09:32,250 --> 00:09:35,130 I get this text here, this ask this. 132 00:09:35,130 --> 00:09:39,960 So is the value of car. 133 00:09:40,960 --> 00:09:44,040 Equal to BMW. 134 00:09:45,140 --> 00:09:47,030 So here our. 135 00:09:49,130 --> 00:09:51,650 W equate equality. 136 00:09:51,860 --> 00:10:00,920 W equal sign asks whether value of this value of a car or a car in this case in is variable, right? 137 00:10:01,130 --> 00:10:10,730 Because we use this car as a variable name and here is the value of car equal to BMW. 138 00:10:10,730 --> 00:10:12,170 In this case it's equal. 139 00:10:12,170 --> 00:10:14,480 So it will return. 140 00:10:14,480 --> 00:10:15,230 True.