1 00:00:00,330 --> 00:00:03,210 ‫Now let's move on to strings in Python. 2 00:00:05,090 --> 00:00:14,850 ‫So how can we pass a string in a Python, if I just write st python tutorial and execute it 3 00:00:21,370 --> 00:00:28,900 ‫I'm getting an error because we need to pass strings in double quotes or single quotes. 4 00:00:30,340 --> 00:00:35,620 ‫So we can write in double quotes st python tutorials. 5 00:00:43,120 --> 00:00:45,400 ‫Here we use double quotation marks. 6 00:00:45,580 --> 00:00:48,610 ‫You can also use single quotes to pass string. 7 00:00:49,510 --> 00:00:54,070 ‫But sometime your string may contain single codes in between. 8 00:00:54,670 --> 00:00:58,810 ‫So therefore, it is recommended to use double quotes while passing strings. 9 00:01:01,610 --> 00:01:04,340 ‫Just like numbers we can also assign 10 00:01:04,610 --> 00:01:13,220 ‫This string to some variable so we can write str one, here str one is our variable and we are assigning 11 00:01:13,220 --> 00:01:15,080 ‫value st Python tutorial. 12 00:01:25,590 --> 00:01:30,000 ‫Now, my str one variable contains this value. 13 00:01:31,800 --> 00:01:40,290 ‫Now, if we want to display the value of our str, one variable, I will just write str one and then 14 00:01:40,290 --> 00:01:41,010 ‫execute this 15 00:01:41,010 --> 00:01:41,400 ‫Command 16 00:01:42,510 --> 00:01:44,580 ‫You can see we are getting our output. 17 00:01:45,780 --> 00:01:51,630 ‫And you can also notice that st python tutorial is coming in quotation marks. 18 00:01:53,010 --> 00:01:57,440 ‫There is also a separate print function in python to print the output. 19 00:01:59,910 --> 00:02:06,850 ‫To print output will write print and in brackets will write str1. 20 00:02:10,670 --> 00:02:13,490 ‫You can now notice that there is no quotation marks. 21 00:02:14,660 --> 00:02:19,450 ‫And now the values are printed and they are not a part of output. 22 00:02:20,750 --> 00:02:26,480 ‫You can see when we just executed str 1, we were getting the content of this variable in 23 00:02:26,480 --> 00:02:27,600 ‫the form of output. 24 00:02:27,770 --> 00:02:30,140 ‫You can see this out written here. 25 00:02:30,530 --> 00:02:34,010 ‫But when we are printing it, python is actually printing it. 26 00:02:34,100 --> 00:02:35,740 ‫And this is not a part of out 27 00:02:38,890 --> 00:02:42,530 ‫Python even provides formatting options with this print function. 28 00:02:44,160 --> 00:02:48,090 ‫So suppose I wanted to use some variable inside my print 29 00:02:48,120 --> 00:02:52,140 ‫Command, I can do that by using print formatting. 30 00:02:53,890 --> 00:03:01,750 ‫For example, in our previous example, in the phrase st python tutorial, I wanted to pass 31 00:03:01,750 --> 00:03:07,150 ‫variable X, which will take python or R depending the value. 32 00:03:12,560 --> 00:03:20,510 ‫So if my x is python, I wanted to print st python tutorial, if my x is R, I wanted to print 33 00:03:20,660 --> 00:03:28,340 ‫Str tutorial or if X is sql, I wanted to print st sql tutorial. 34 00:03:30,390 --> 00:03:34,320 ‫So let's create this variable X and assign it value R 35 00:03:38,200 --> 00:03:43,970 ‫Notice that we are using double codes to assign value to this variable. 36 00:03:47,180 --> 00:03:48,590 ‫We will first write print 37 00:03:52,240 --> 00:03:59,680 ‫And in brackets we will put quotation marks and will pass the array string, which is S-T. 38 00:04:02,040 --> 00:04:10,200 ‫And then since I want my second word to be this variable X, I will give curly brackets. 39 00:04:12,130 --> 00:04:15,120 ‫And my third word is a constant, which is tutorial 40 00:04:15,520 --> 00:04:17,110 ‫So I will write tutorial. 41 00:04:21,590 --> 00:04:25,820 ‫Now, I want to tell Python what goes inside this curly bracket. 42 00:04:26,270 --> 00:04:28,910 ‫So after this print command, I will put a Dot 43 00:04:31,010 --> 00:04:38,800 ‫And write format and in parenthesis, I can write my variable name, which is X. 44 00:04:42,530 --> 00:04:43,340 ‫Let's run this. 45 00:04:45,340 --> 00:04:50,800 ‫We are getting this error because dot format should be inside the print 46 00:04:50,840 --> 00:04:51,250 ‫Command. 47 00:04:51,740 --> 00:04:54,290 ‫So we just copy paste it 48 00:05:00,270 --> 00:05:00,380 ‫Yes. 49 00:05:01,140 --> 00:05:04,770 ‫And now if we execute it, you can see we are getting 50 00:05:05,590 --> 00:05:07,020 ‫Str, tutorial. 51 00:05:09,090 --> 00:05:17,070 ‫If I change my value of X to SQL and then again run this print command 52 00:05:18,360 --> 00:05:22,350 ‫You can see now since our X is SQL. 53 00:05:24,610 --> 00:05:27,760 ‫The output is statement is st sql tutorial. 54 00:05:29,410 --> 00:05:33,480 ‫So what's happening here is, the curly bracket in print command tells 55 00:05:33,690 --> 00:05:37,960 ‫Python to take the value of variable that is mentioned in the dot format 56 00:05:38,230 --> 00:05:39,010 ‫Parentheses. 57 00:05:41,340 --> 00:05:44,970 ‫If I want, I can also pass two or more than two variables. 58 00:05:45,330 --> 00:05:47,910 ‫The syntax will remain the same in that case. 59 00:05:49,200 --> 00:05:55,080 ‫And you have to mention the variable names in dot format in the order you want them to be filled 60 00:05:55,130 --> 00:05:56,030 ‫in the curly bracket. 61 00:05:57,700 --> 00:05:59,460 ‫So if we just write print. 62 00:06:03,310 --> 00:06:06,190 ‫And in bracket will write S.T.. 63 00:06:10,620 --> 00:06:13,810 ‫Then curly brackets, here our variable X will come. 64 00:06:14,770 --> 00:06:16,810 ‫Then after this tutorial 65 00:06:20,140 --> 00:06:21,610 ‫and then another curly bracket. 66 00:06:25,940 --> 00:06:36,800 ‫And in dot, we can write X and the variable we created earlier, that was var one if we execute this. 67 00:06:38,630 --> 00:06:42,620 ‫You can see our var one variable was containing 14. 68 00:06:43,920 --> 00:06:47,970 ‫So our printed string is st sql tutorial 14. 69 00:06:49,710 --> 00:06:53,340 ‫Now let's discuss some important functions related to strings. 70 00:06:54,570 --> 00:06:55,650 ‫The first function. 71 00:06:56,900 --> 00:06:57,830 ‫Is length function. 72 00:06:58,250 --> 00:07:01,040 ‫It helps us to find the length of our string. 73 00:07:02,980 --> 00:07:06,370 ‫The syntax of length function is l e n. 74 00:07:08,150 --> 00:07:16,070 ‫Now, if we want to check the length of our str 1 variable we can just mention str one inside parenthesis 75 00:07:16,130 --> 00:07:16,820 ‫After length 76 00:07:18,830 --> 00:07:21,830 ‫You can see the length of our variable str one. 77 00:07:22,220 --> 00:07:23,330 ‫Is 18 78 00:07:25,000 --> 00:07:27,850 ‫Also note that is space is also a character. 79 00:07:28,000 --> 00:07:29,770 ‫So this length 18. 80 00:07:30,840 --> 00:07:37,150 ‫Is count of all the characters, including spaces and other punctuation marks as well. 81 00:07:39,810 --> 00:07:44,010 ‫Another string function, which we frequently used, is replace function. 82 00:07:46,380 --> 00:07:53,700 ‫You must have used replace function in word or notepad, where you search the word and then replace 83 00:07:53,700 --> 00:07:58,530 ‫that word with a new word, replace function in python works 84 00:07:58,710 --> 00:07:59,760 ‫Exactly the same. 85 00:08:00,950 --> 00:08:02,390 ‫You have to give two words. 86 00:08:04,960 --> 00:08:06,790 ‫.First, the word you want to search. 87 00:08:06,970 --> 00:08:09,930 ‫And second, the word you want to replace it with. 88 00:08:11,420 --> 00:08:14,730 ‫So let's again print our str 1 variable 89 00:08:18,180 --> 00:08:18,740 ‫right now. 90 00:08:19,170 --> 00:08:23,060 ‫My str one contains st python tutorial. 91 00:08:24,420 --> 00:08:36,180 ‫If I want to replace this word python with sql, I will write str one dot replace and in 92 00:08:36,180 --> 00:08:40,200 ‫Brackets first the word I want to replace. 93 00:08:41,700 --> 00:08:42,620 ‫That is Python. 94 00:08:45,660 --> 00:08:48,750 ‫Also remember that Python is case sensitive language. 95 00:08:49,960 --> 00:08:56,110 ‫So I have to pass python in lowercase since my variable contained python in lowercase. 96 00:08:56,380 --> 00:08:59,460 ‫I want to replace this variable with sql. 97 00:09:00,550 --> 00:09:03,660 ‫So after a comma, I will write a sql. 98 00:09:09,870 --> 00:09:12,480 ‫You can see that the word by python. 99 00:09:13,710 --> 00:09:16,040 ‫Has now been replaced with sql. 100 00:09:17,360 --> 00:09:20,440 ‫I can also save this value in another variable. 101 00:09:21,530 --> 00:09:25,100 ‫So let's save this value in another variable called x. 102 00:09:30,600 --> 00:09:33,780 ‫I will copy paste sole function. 103 00:09:41,110 --> 00:09:42,090 ‫If I print x 104 00:09:45,410 --> 00:09:47,990 ‫I'll get this, value st sql tutorial. 105 00:09:50,540 --> 00:09:55,190 ‫Now let's move on to string indexes and a string slicing. 106 00:09:56,350 --> 00:10:00,220 ‫You can see string is a collection of several individual characters. 107 00:10:01,120 --> 00:10:09,060 ‫For example, in our variable X, s is a single character, t is a single character. 108 00:10:10,170 --> 00:10:13,920 ‫And our whole string is a collection of such characters. 109 00:10:15,620 --> 00:10:19,540 ‫These characters are present at a specified position in our string. 110 00:10:20,240 --> 00:10:28,640 ‫So, for example, s is present at the first position, t is present at the second position. 111 00:10:29,510 --> 00:10:31,640 ‫And similarly, we have a space 112 00:10:31,760 --> 00:10:32,950 ‫At the third position. 113 00:10:36,000 --> 00:10:41,910 ‫We can extract this individual characters from a variable by specifying their positions. 114 00:10:42,840 --> 00:10:51,390 ‫This concept of extracting characters by their position is known as string indexing or string slicing. 115 00:10:53,040 --> 00:10:58,940 ‫One thing to note here is that in python, indexing starts with zero. 116 00:11:02,180 --> 00:11:12,080 ‫So our character s is present at zero th Index t is present at first index and space is present at 117 00:11:12,890 --> 00:11:13,760 ‫two index. 118 00:11:15,810 --> 00:11:21,770 ‫So if I want to extract the character which is present at the first index, I will just write our 119 00:11:21,780 --> 00:11:27,960 ‫Variable name, which is X and then the square bracket, I will mention the index, which is one. 120 00:11:32,970 --> 00:11:36,870 ‫If we execute this, we will get t 121 00:11:36,990 --> 00:11:41,430 ‫As our output since t was present at the first Index. 122 00:11:43,190 --> 00:11:46,520 ‫Position is different from index, the position of t is two. 123 00:11:46,790 --> 00:11:53,760 ‫But since the index starts from zero, our s was present at 0th index and our t was present at 124 00:11:53,790 --> 00:11:54,680 ‫First index. 125 00:11:57,540 --> 00:11:59,880 ‫I can also mention multiple index. 126 00:12:00,210 --> 00:12:05,850 ‫So if I want all characters which are present from index two to index five. 127 00:12:08,140 --> 00:12:10,570 ‫I will write X and in squared bracket 128 00:12:10,840 --> 00:12:11,950 ‫I will write two. 129 00:12:14,090 --> 00:12:18,890 ‫Then I will provide a colon symbol and then I will write five. 130 00:12:20,030 --> 00:12:25,490 ‫This means that I want all characters which are present between index two and five. 131 00:12:27,760 --> 00:12:34,990 ‫Notice that our first character is space, our second character is s, and our third character is 132 00:12:35,020 --> 00:12:35,590 ‫Q. 133 00:12:37,730 --> 00:12:45,120 ‫We are getting all the characters that are present at index two index three, and index four. 134 00:12:46,350 --> 00:12:54,720 ‫We are not getting our indexed five variable because the second argument is always excluded while slicing 135 00:12:54,720 --> 00:12:57,090 ‫the string using indexes. 136 00:12:58,550 --> 00:13:05,420 ‫So two colon five means character present at index two, three and four. 137 00:13:08,840 --> 00:13:17,810 ‫Similarly, if we write bracket four Colon six, it will return the characters which are present at 138 00:13:17,810 --> 00:13:19,190 ‫index four and five. 139 00:13:21,080 --> 00:13:28,700 ‫Index six will be excluded from our selection. indexes, also supports negative argument. 140 00:13:30,110 --> 00:13:33,560 ‫Negative stands for counting from the backside of this string. 141 00:13:35,000 --> 00:13:41,630 ‫So minus one will be the last character of string, minus two will be the second last character and 142 00:13:41,630 --> 00:13:42,200 ‫so on. 143 00:13:44,150 --> 00:13:51,260 ‫So if I wanted to print last character of my string, I will write X and in square record I will 144 00:13:51,260 --> 00:13:53,300 ‫mention minus one. 145 00:13:58,060 --> 00:14:06,100 ‫We are getting l as our output since the last character or our variable X was l 146 00:14:10,150 --> 00:14:14,260 ‫While slicing you can also skip the arguments. 147 00:14:14,680 --> 00:14:16,360 ‫So if I write X. 148 00:14:18,760 --> 00:14:21,610 ‫And in square bracket, I will write colon five. 149 00:14:25,110 --> 00:14:30,750 ‫This means that I want all the characters from the start of my string till the index five. 150 00:14:31,440 --> 00:14:32,250 ‫If I run this. 151 00:14:36,140 --> 00:14:39,380 ‫You can see we are getting all the characters from the start of this string. 152 00:14:40,490 --> 00:14:45,230 ‫Similarly, if I want all the characters from Index five. 153 00:14:46,220 --> 00:14:51,440 ‫To the end of the string, I will write X and in bracket, I will write five colon. 154 00:14:54,820 --> 00:15:00,020 ‫You can see all the characters from the fifth index is present in our output. 155 00:15:03,190 --> 00:15:07,210 ‫Now, what if, if I wanted alternate characters from my string. 156 00:15:08,580 --> 00:15:13,410 ‫I can do that by mentioning the third parameter, which is the step parameter. 157 00:15:14,520 --> 00:15:17,580 ‫So earlier we were passing only two parameters. 158 00:15:17,850 --> 00:15:19,020 ‫The starting point. 159 00:15:19,440 --> 00:15:22,350 ‫And then after the colon, we were passing the end point. 160 00:15:24,080 --> 00:15:29,510 ‫We can also pass the third argument after another colon symbol as a step argument 161 00:15:31,220 --> 00:15:37,700 ‫So if I write X and in squared bracket, I will write two colon ten. 162 00:15:41,280 --> 00:15:49,620 ‫This means I want all the characters from index to index nine, remember index 10 is excluded 163 00:15:52,510 --> 00:16:04,420 ‫But if I write 2 colon 10 colon 2, this means I want characters with step as two so I will be getting 164 00:16:04,480 --> 00:16:06,630 ‫characters present at index 2. 165 00:16:07,570 --> 00:16:11,290 ‫And since our step is two it will directly jump to index four. 166 00:16:14,280 --> 00:16:18,000 ‫And then to index six and then to index eight. 167 00:16:19,390 --> 00:16:19,920 ‫If I run this 168 00:16:22,340 --> 00:16:28,160 ‫If I print my x just to compare our output, you can see. 169 00:16:30,200 --> 00:16:35,050 ‫Our character at index two was space. 170 00:16:38,590 --> 00:16:41,440 ‫Character at Index Four was q. 171 00:16:44,030 --> 00:16:53,120 ‫Then character at Index six was again space and then character at Index 172 00:16:53,210 --> 00:16:54,500 ‫8 was u. 173 00:16:57,820 --> 00:17:04,140 ‫Similarly, if you want to change this step size to three, four or anything, you can do that. 174 00:17:08,010 --> 00:17:13,850 ‫One thing you may have noticed is that we are not defining variables while creating the variables. 175 00:17:16,200 --> 00:17:22,950 ‫As with other programming languages such as the C, SQL or C++, we don't have to define variable 176 00:17:22,950 --> 00:17:24,030 ‫types in Python. 177 00:17:25,600 --> 00:17:30,430 ‫Python will automatically assign that type depending on the value present in that variable. 178 00:17:32,520 --> 00:17:40,380 ‫So if you are passing variable X as one python will automatically assign X as an integer. 179 00:17:41,130 --> 00:17:48,990 ‫If you are passing X as an string, it will automatically assign X as an string or if you are passing 180 00:17:49,440 --> 00:17:50,860 ‫it as a decimal point. 181 00:17:52,200 --> 00:17:53,930 ‫It will get a floating point type. 182 00:17:55,940 --> 00:18:03,950 ‫To know the type of variable we can use type function, we just have to write type and in parenthesis, 183 00:18:04,020 --> 00:18:04,190 ‫Write 184 00:18:04,290 --> 00:18:05,050 ‫The variable name. 185 00:18:06,090 --> 00:18:10,730 ‫here we will write X and we should get a string as our output. 186 00:18:11,730 --> 00:18:12,420 ‫You can see. 187 00:18:13,630 --> 00:18:16,510 ‫The type of our variable X is str. 188 00:18:17,410 --> 00:18:18,130 ‫Similarly. 189 00:18:19,520 --> 00:18:22,820 ‫If we get the type of our variable that is. 190 00:18:25,690 --> 00:18:26,560 ‫Variable one. 191 00:18:29,310 --> 00:18:29,920 ‫We are getting. 192 00:18:30,060 --> 00:18:34,830 ‫And since our variable one was containing 14 as a value. 193 00:18:38,810 --> 00:18:46,940 ‫Now, if we assign variable 2 a value of five divided by two and we print this variable 2, 194 00:18:46,940 --> 00:18:52,370 ‫too, you can see that variable 2, is taking a value 2.5. 195 00:18:53,210 --> 00:18:59,390 ‫If we want to get the type of this variable to, we will write type and in bracket will write. 196 00:18:59,390 --> 00:19:06,330 ‫Variable 2 we should be getting floating number as decimal is present in our value.