Difference between revisions of "C-and-C++/C3/Strings/English-timed"

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|To read a '''string''', we can use '''scanf() function''' with format specifier '''%s'''.
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|To read a '''string''', we can use '''scanf()''' function with format specifier '''%s'''.
  
 
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|Delete the '''scanf''' statement and type '''getline opening bracket closing bracket within the brackets type(cin, strname) '''.
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|Delete the '''scanf''' statement and type '''getline opening bracket closing bracket''', within the brackets type '''(cin, strname) '''.
  
 
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|More information on this Mission is available at the link shown below.
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|More information on this mission is available at the link shown below.
  
 
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Revision as of 21:32, 15 February 2015

Time Narration
00:01 Welcome to the spoken-tutorial on Strings in C and C++.
00:06 In this tutorial we will learn:
00:08 * What is a string.
00:10 * Declaration of a string.
00:13 * Initialization of a string.
00:15 * Few examples on string.
00:17 We will also see some common errors and their solutions.
00:22 To record this tutorial, I am using
00:25 Ubuntu Operating System version 11.04,
00:29 gcc and g++ Compiler version 4.6.1 .
00:35 Let us start with the introduction to strings.
00:38 String is a sequence of characters that is treated as a single data item.
00:44 Size of string = length of string + 1.
00:49 Let me tell you how to declare a string.
00:52 The syntax for this is
00:55 char, name of string and size.
00:59 char is the data type, name of the string is the string name, and we can give the size here.
01:06 Eg: here we have declared a character string names with size 10.
01:13 Now we will see an example.
01:15 I have already typed the program, I will open it.
01:19 Note that our file name is string.c
01:23 In this program, we will take a string as an input from the user and print it.
01:29 Let me explain the code now.
01:32 These are our header files.
01:34 Here string.h includes the declarations, functions, constants of string handling utilities.
01:43 Whenever we work on string functions, we should include this header file.
01:47 This is our main() function.
01:49 Here we are declaring the string strname with size 30.
01:55 Here we are accepting a string from the user.
01:58 To read a string, we can use scanf() function with format specifier %s.
02:05 We are using the caret sign and \n to include the spaces with the string.
02:11 Then we print the string.
02:13 And this is our return statement.
02:16 Now click on Save.
02:18 Let us execute the program.
02:20 Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
02:30 To compile, type gcc space string.c space -o space str
02:37 And press Enter .
02:40 To execute, type ./str (dot slash str).
02:43 Now press Enter.
02:46 Here it is displayed as Enter the string .
02:49 I will type "Talk To A Teacher".
02:56 Now press Enter.
02:58 The output is displayed as The string is Talk To A Teacher.
03:03 Now let us switch back to our slides.
03:06 Until now we discussed about the declaration of a string.
03:10 Now we are going to discuss how to initialize the string.
03:13 The syntax for this is,
03:16 char var_name[size] = “string”;
03:20 Eg: Here we have declared a character string “names” with size 10 and the string is “Priya”"
03:28 Another syntax is,
03:31 char var_name[ ] = {'S', 't', 'r', 'i', 'n', 'g'} within single quotes.
03:36 eg: char names[10] = {'P', 'r', 'i', 'y', 'a'} in single quotes.
03:42 Let me show you how to use the first syntax with an example.
03:48 Switch back to our Editor. We will use the same example.
03:52 First, press shift, ctrl and s keys simultaneously on your keyboard.
03:58 Now save the file with the name stringinitialize.
04:03 Now click on Save.
04:06 We are going to initialize the string.
04:08 Hence, at the 5th line, type
04:11 = and within the double quotes “Spoken-Tutorial”;
04:20 Now, click on Save .
04:22 Now remove these two lines, as we are only going to print the string.
04:27 Click on Save.
04:30 Let us execute.
04:31 Come back to our terminal.
04:33 To compile, type
04:35 gcc space stringinitialize.c space -o space str2
04:44 Here we have str2 because we don't want to overwrite the output parameter str for the file string.c.
04:54 Now press Enter.
04:56 To execute, type ./str2
05:00 The output is displayed as "The string is Spoken-Tutorial".
05:06 Now we will see some common errors which we can come across .
05:09 Come back to our program.
05:11 Suppose, here we type the spelling of string as sting.
05:16 Now click on Save.
05:18 Let us execute.
05:19 Come back to our terminal.
05:21 Now compile as before.
05:23 We see an fatal error.
05:25 sting.h: No such file or directory
05:28 compilation terminated.
05:30 Come back to our program.
05:32 This is because the compiler is not able to find the header file with the name sting.h .
05:39 Hence it is giving an error.
05:41 Let us fix the error.
05:43 Type r here.
05:45 Now click on Save.
05:46 Let us execute again.
05:47 Come back to our terminal.
05:50 Compile as before, execute as before.
05:54 Yes, it is working!
05:56 Now, let us see another common error.
05:59 Come back to our program.
06:02 Suppose, here I will type int in place of char.
06:06 Now, click on Save .
06:07 Let us see what happens.
06:09 Come back to our terminal.
06:11 Let me clear the prompt.
06:15 Compile as before.
06:17 We see an error.
06:19 Wide character array initialized from non-wide string .
06:24 format %s expects argument of type 'char' but argument 2 has type 'int' .
06:32 Come back to our program.
06:36 This is because we used  %s as the format specifier for string.
06:42 And we are initializing it with an integer data type.
06:47 Let us fix the error.
06:49 Type char here.
06:51 Click on Save.
06:53 Let us execute. Come back to our terminal.
06:56 Compile as before, execute as before.
07:00 Yes, it is working!
07:03 Now we will see how to execute the same program in C++.
07:08 Come back to our program.
07:11 Let me open our file string.c.
07:15 We will edit the code here.
07:18 First, press shift, ctrl and S keys simultaneously on your keyboard.
07:25 Now save the file with an extension .cpp (dot cpp).
07:29 and click on Save.
07:33 Now we will change the header file as iostream.
07:38 Include the using statement.
07:43 Now click on Save.
07:47 Now we will delete this declaration.
07:50 And will declare a string variable.
07:53 Type string space strname and a semicolon.
07:59 Click on Save.
08:02 Replace the printf statement with the cout statement.
08:07 Delete the closing bracket here.
08:11 Delete the scanf statement and type getline opening bracket closing bracket, within the brackets type (cin, strname) .
08:24 At the end, type a semicolon.
08:28 Now again, replace the printf statement with the cout statement.
08:36 Delete the format specifier and \n .
08:40 Now delete the comma.
08:42 Type two opening angle brackets, delete the bracket here.
08:49 Type two opening angle brackets and within the double quotes type \n .
08:54 And click on Save.
08:58 Here we have declared a string variable 'strname' .
09:03 Since we do not use the format specifier in C++, the compiler should know that 'strname' is a string variable.
09:13 Here we use getline to extract the characters from the input sequence.
09:18 It stores them as a string.
09:22 Now let us execute the program. Come back to our terminal.
09:27 Let me clear the prompt.
09:30 To compile, type
09:32 g++ space string.cpp space -o space str3
09:39 and press Enter.
09:41 To execute, type ./str3 (dot slash str3).
09:46 Press Enter.
09:47 It is displayed as Enter the string.
09:50 I will enter as Talk To A Teacher .
09:55 Now press Enter.
09:57 The output is displayed as
09:59 "The string is Talk To A Teacher"
10:03 We can see that the output is similar to our C code.
10:07 Now come back to our slides.
10:10 Let us summarize.
10:11 In this tutorial we learnt:
10:13 *Strings
10:14 *Declaration of a string
10:16 eg: char strname[30]
10:20 *Initialization of a string
10:21 eg: char strname[30] = “Talk To A Teacher”
10:26 As an assignment,
10:28 write a program to print a string using the 2nd syntax.
10:34 Watch the video available at the link shown below.
10:37 It summarizes the Spoken Tutorial project.
10:40 If you do not have good bandwidth, you can download and watch it.
10:44 The Spoken Tutorial Project Team:
10:46 Conducts workshops using spoken tutorials.
10:49 Gives certificates to those who pass an online test.
10:54 For more details, please write to, contact@spoken-tutorial.org.
11:01 Spoken Tutorial Project is a part of Talk to a Teacher project.
11:04 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
11:12 More information on this mission is available at the link shown below.
11:16 This is Ashwini Patil from IIT Bombay, signing off.
11:20 Thank You for watching.

Contributors and Content Editors

Kavita salve, PoojaMoolya, Pratik kamble, Sandhya.np14

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