C-and-C++/C3/Strings/English

Title of script: Strings

Author: Ashwini R Patil

Keywords: Strings in C, getline, Video Tutorial

Visual Cue	Narration
Slide 1	Welcome to the spoken-tutorial on Strings in C and C++
Slide 2 Learning Objectives	In this tutorial, we will learn, What is a string. Declaration of a string. Initialization of a string. Few examples on string. We will also see some common errors and their solutions
Slide 3 System Requirements	To record this tutorial, I am using Ubuntu Operating System version 11.04 gcc and g++ Compiler version 4.6.1
Slide 4 Introduction to strings	Let us start with the Introduction to the Strings String is a sequence of characters that is treated as a single data item size of string = length of string + 1
Slide 5 Declaration of the String Syntax: char val[10];	Let me tell you how to declare a string The syntax for this is char name_of_string[size]; char, name of string and size char is the data type, name of the string is the string name, and we can give the size here. Eg: here we have declared a character string names with size 30
Please open the Terminal	Now we will see an example I have already typed the program I will open it Note that our file name is string.c In this program we will take a string as an input from the user and print it Let me explain the code now
Highlight #include<string.h>	These are out header files here string.h includes the declarations, functions, constants of string handling utilities Whenever we work on string functions, we should include this header file
Highlight char strname[30];	This is our main function Here we are declaring the string 'strname' with size '30'
Highlight printf("Enter the string\n");	Here we are accepting a string from the user
Highlight scanf("%[^\n]s",strname);	To read a string, we can use scanf() function with format specifier %s We are using the caret sign and \n to include the spaces with the string
Type: printf("The string is %s\n", strname);	Then we print the string And this is our return statement
Save the program	Now click on Save
Execution of the program On the terminal	Let us execute the program Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard
Type gcc strdeclare.c str >> press Enter	To compile Type gcc space string.c space -o space str And press Enter
Type ./str >> press Enter	To execute, type ./str now press Enter
	Here it is displayed as Enter the string
Type Talk To A Teacher >> press Enter	I will type Talk To A Teacher now press Enter
Highlight Output	The output is displayed as The string is Talk To A Teacher
Slide 6 Initialization of the string Syntax: char strinitialize[20] = “star”; (or) char strinitialize[] = {'S', 't', 'r'};	Now let us switch back to our slides Until now we discussed about the declaration of a string Now we are going to discuss how to initialize the string The syntax for this is char var_name[size] = “string”; eg: here we have declared a character string names with size 30 and the string is Priya Another syntax is char var_name[ ] = {'S', 't', 'r', 'i', 'n', 'g'}; within single quotes eg: char names[10] = {'P', 'r', 'i', 'y', 'a'}; in single quotes
Please switch to the Text editor	Let me show you how to use the first syntax with an example Switch back to our Editor We will use the same example
Click on File >> Save as option Type strinitialize.c	First press shift, cntrl and s key simultaneously on your keyboard now save the file with the name strinitialize.c
Click on save	Now click Save
Type char name[30] = "Talk To A Teacher";	We are going to intialize this string Hence at the 5th line type = and within double quotes “Spoken- Tutorial”; now click on save
Delete printf("Enter the string\n"); scanf("%[^\n]s",strname);	Now remove these two lines as we are only going to print the string click on save
Save the program	let us execute
On the terminal Type gcc strinitialize.c -o str1	Come back to our terminal To compile Type gcc space stringintialize.c space -o space str2
To execute Type ./str1	Here we have str2 because we dont want to overwrite the output parameter str for the file string.c now press Enter To execute type ./str2
Highlight Output	The output is displayed as The string is Spoken-Tutorial
Error1 Type sting.h	Now we will see some common errors which we can come across Come back to our program Suppose here we type the spelling of string as sting
Click on Save	Now click on Save
On the terminal	Let us execute, come back to the terminal
Compile and execute as before gcc strinitialize.c -o str1 ./str1	Now compile as before We see a fatal error sting.h no such file or directory compilation terminated
On the editor, correct the spelling	Come back to the program This is because the compiler is not able to find the header file with the name sting.h Hence it is giving an error Let us fix the error Type r here now click on save
On the terminal	Let us execute again Come back to our terminal Compile as before, execute as before Yes it is working!
Error2 Type int	Now let us see another common error come back to our program Suppose here I will type int in place of char now click on save Let us see what happens Come back to our terminal
On the terminal	Let me clear the prompt Compile as before We see an error Wide charactr array initialized from non-wide string format %s expects argument of type 'char' But argument 2 has type 'int' come back to our program this is because we used %s as the format specifier for string And we are initializing it with an integer data type int
On the editor	Let us fix the error Type 'char' here click on save let us execute
Click on save	Click on Save
On the terminal	Come back to our terminal Compile as before, execute as before
	Yes it is working!
On the editor	NOW WE WILL SEE HOW TO EXECUTE THE SAME PROGRAM IN C++ Come back to our program
Click on File Save as Type .cpp	Let me open our file string.c We will edit the code here First press shift, cntrl and S key simultaneously on your keyboard Now save the file with an extension .cpp and click on save
Type iostream	Now we will change the header file as iostream
Type #include <string>	Include the using statement now click on save now we will delete this declaration
Type string strname;	and declare a string variable, type string space strname and a semicolon Click on save
Type cout <<	Replace the printf statement with cout statement delete the closing bracket here
Delete scanf Type getline(cin, strname);	Delete the scanf statement and Type getline(cin, strname) at the end type a ;
Type cout <<"The string is " <<strname <<"\n"; In place of printf("The string is %s\n",strname);	Again replace the printf statement with cout statement Delete the format specifier and \n Now delete the , Type two opening angle brackets, delete the bracket here type two opening angle brackets and within the double quotes type \n
Click on save	And click on Save
	we have declared a string variable 'strname' since we do not use the format specifier in C++ the compiler should know that strname is a string variable Here we use getline to extract the characters from the input sequence, it stores them as a string
On the terminal	Now let us execute the program, Come back to our terminal
	Let me clear the prompt
Type g++ string.cpp -o str1	To compile type g++ space string.cpp space -o space str3 and press Enter
Type ./str1	To execute type ./str3 Press enter
Highlight >> type Talk To A Teacher	It is displayed as Enter the string I will enter as Talk To A Teacher Now press Enter
	The output is displayed as The string is Talk To A Teacher We can see that the output is similar to our C code Now come back to our slides
Slide 7	Let us summarize In this tutorial we learnt Strings Declaration of a string eg: char strname[30] Initialization of a string eg: char strname[30] = “Talk To A Teacher”
Slide 8 Assignment	As an assignment Write a program to print a string using the 2nd syntax
Slide 9 About the Spoken Tutorial Project	Watch the video available at the link shown http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it
Slide 10 Spoken Tutorial Workshops	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, Please write to contact@spoken-tutorial.org
Slide 11 Acknowledgement	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro
	Ashwini Patil from IIT Bombay Thank You for joining

Contributors and Content Editors

Ashwini, Nancyvarkey