C-and-C++/C3/String-Library-Functions/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	In this tutorial, we will learn, What is a string. Declaration of the string. Initialization of the string. With the help of an example. We will aldo see some common errors and their solutions
Slide 3	To record this tutorial, I am using Ubuntu Operating System version 11.04 gcc and g++ Compiler version 4.6.1 on ubuntu
Slide 4	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 = original 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];
Please open the Terminal	Now we will see how to declare a string with an example I have already typed the program So I will just open it Note that I have saved the file with the name string.c Let me explain the code now
Highlight #include<string.h>	Here, string.h is a header file It 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];	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 Here we are using the caret sign and \n to include the spaces with the string
Type: printf("The string is %s\n", strname);	Here we print the string
Save the program	Now click on Save to save the program
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
Type gcc strdeclare.c str >> press Enter	To compile Type gcc strdeclare.c str And press Enter
Type ./str >> press Enter	To execute, type ./str and press Enter
	Enter the string is displayed here
Type Talk To A Teacher >> press Enter	I will type Talk To A Teacher and press Enter
Highlight Output	And 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'};	Let us switch back to the slides Until now we discussed about the declaration of a string Now we are going to discuss how to initialize the string This is done by specifying the value To initialize a string the syntax is char var_name[size] = “string”; (or) char var_name[] = {'S', 't', 'r'};
Please switch to the Text editor	Let me show you how to use the first syntax with an example Please switch back to the Text Editor Let me use the same example
Click on File >> Save as option Type strinitialize.c	First click on File menu Click on Save as option Let us save the file with the name strinitialize.c
Click on save	Now click on Save
Type char name[30] = "Talk To A Teacher";	Let us change a few things here Let us replace the 5th line with char strname [30] = “Talk To A Teacher”; Here we have initialized a character array strname with size '30'
Delete printf("Enter the string\n"); scanf("%[^\n]s",strname);	Please remove the next two lines as we only want to print the string We are not taking the string as input from the user
Save the program	Now let us save the program and execute it
On the terminal Type gcc strinitialize.c -o str1	Come back to the terminal Let us compile as before Type gcc strinitialize.c -o str1
To execute Type ./str1	To execute Type ./str1
Highlight Output	Here the output is displayed as The string is Talk To A Teacher
Error1 Type sting.h	Let us see some common errors which we can come across Suppose here we type the spelling of string as sting
Click on Save	I will retain rest of the code as it is Click on Save
On the terminal	To execute the program, we will go on the terminal
Compile and execute as before gcc strinitialize.c -o str1 ./str1	Let us compile and execute as before We see that there is a fatal error The compiler is not able to find the header file with the name <sting.h> Hence the compilation is terminated
On the editor, correct the spelling	Let us fix this error Come back to the program Type r here
On the terminal	Come back on the terminal Let us compile and execute as before Yes it is working!
Error2 Type int	Let us see another common error Suppose I type int here in place of char Let us see what happens Come back on the terminal
On the terminal	Let us compile and execute as before We see there is an error and a warning The format specifier for string is %s And we are declaring it with an integer data type int
On the editor	Let us fix the error Come back to our program Let us type char here
Click on save	Click on Save
On the terminal	Come back to our terminal Let us compile and execute as before
	Yes it is working!
On the editor	NOW LET US SEE HOW TO EXECUTE THE SAME PROGRAM IN C++ Come back to our program
Click on File Save as Type .cpp	First let us save the file with an extention .cpp Click on File menu Click on Save as option Now save the file with an extension .cpp
	Let me change a few things here
Type iostream	First we will change the header file as iostream
Type #include <string>	We will include another header file here Type #include <string>
Type using namespace std;	We will include the using statement here
Type string strname;	Let us define a string variable strname Since we don't use the format specifier in C++ , the compiler should know that strname is a string variable
Type cout <<	Now replace the printf statement with cout statement
Delete scanf Type getline(cin, strname);	Now delete the scanf statement here and Type getline(cin, strname);
	We use getline to extract the characters from the input sequence It stores them as a string
Type cout <<"The string is " <<strname <<"\n"; In place of printf("The string is %s\n",strname);	Now again replace the printf statement with cout statement Delete the format specifier and \n here Type two opening angle brackets Then again type two opening angle brackets here and type within the double quotes \n Delete the closing bracket here
Click on save	Now click on Save
On the terminal	Come back on the terminal
Type g++ string.cpp -o str1	To compile type g++ string.cpp -o str1
Type ./str1	To execute type ./str1
Highlight >> type Talk To A Teacher	Enter the string is displayed here I will type Talk To A Teacher
	The output is displayed as The string is Talk To A Teacher
Slide 7 Assignment	As an assignment Write a program to print a string using the 2nd syntax
Slide 8 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 9 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 10 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