C-and-C++/C3/String-Library-Functions/English

Title of script: String Library Functions

Author: Ashwini R. Patil

Keywords: String Library Functions, strcpy, strcat, strlen, Video Tutorial

Visual Cue	Narration
Slide 1	Welcome to the spoken-tutorial on String Library Functions in C
Slide 2 Learning Objectives	In this tutorial, we will learn, String Library Functions We will do this with the help of some examples
Slide 3 System Requirements	To record this tutorial, I am using Ubuntu Operating System version 11.10, gcc Compiler Version 4.6.1
Slide 4 Introduction to the standard library funtions	Let us start with an introduction to string library functions. These are the group of functions implementing operations on strings. Various operations such as copying, concatenation, searching etc are supported.
Slide 5 String Library functions	Let us see some of the string library functions Here we have the strncpy function The syntax for this is strncpy(char str1, char str2, (and) int n ) It copies first n characters of string str2 into string str1. eg. char strncpy(char hello, char world, 2); The output will be Wollo Here we have Wo from the string 2 and rest of the characters from string 1
Slide 6	Now we will see strcmpy function , the syntax for this is (char str1, char str2, int n) It will compare first n characters of string 2 with string 1 eg. int strmcmp(char ice, char icecream, (and) int 2); The output will be 0
Examples of some commonly used String functions Please open the Text Editor Go to Applications – Accessories – Text Editor	Now we will see how to use the string library functions. I am going to show you some of the commonly used string functions. I have already typed the program on the editor, i will open it Here we have the string length function
//strlen()	Note that our filename is strlen.c. In this we will find the length of the string These are the header files as stdio.h and string.h This is our main function
Highlight char arr[] = "Icecream";	Here we have a character variable 'arr', It stores a value 'Ashwini' Then we have an integer variable len1
Highlight int len1 = strlen(arr);	Here we will find the length of the string using strlen funtion the result will be stored in len1
Highlight printf("string = %s length = %d\n", arr, len1);	Then we print the string and the length of the string. And this is our return statement
Execution of the program Ctrl, Alt and T keys simultaneously	Now let us execute the program Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard
Type gcc strlen.c -o len	To compile Type: "gcc" space "strlen.c" space “-o” space “str1”. Press Enter
Type ./str1	type: ./str1 Press Enter
Highlight Output	The output is displayed as string = Ashwini, Length = 7 You can count here. 1,2,3,4,5,6, and 7
	Let us see another string function Here we have the string copy fuction
//strcpy	Note that our filename is strcpy.c
Highlight strcpy(target, source);	In this we will copy the source string into the target string Here we have Ice in the source string, it will be copied to the target string This is our strcpy function.
Highlight printf("source string = %s\n",source);	Here we print the source string and the target string
Execution of the program Please Switch back to the terminal	Let us execute and see Come back to our terminal
	To compile type gcc space strcpy.c space -o space str2 Press Enter Type ./str2 Press Enter Everywhere you change the file name and tell them to compile as before. Yes, i want an explanation? * Ignore this, i deleted.
Highlight Output	The output is displayed as source string = Ice target string = Ice
	Now let us see another string function
//strcat	Now we will see the string compare function Note that our filename is strcmp.c In this we will comapre two strings Here we have character variables as str1 and str2
Highlight char source[]= "World"; char target[]= "Hello";	str1 stores the value as 'Ice' and str2 stores the value as 'Cream'. Here we have interger variables as i and j. In this we will compare the string using the strcmp function. Here we compare str1 ie: 'Ice' with 'Hello'. The result is stored in i. In this we will compare string 2 ie: 'Cream' with 'Cream'. The result is stored in j. Then we print both the results. and this is our return statement.
Execution of the program Please switch back to the terminal	Let us execute the program. Come back to our terminal.
	To compile type gcc space strcmp.c space -o space str3 Press Enter Type ./str3 The outpur is displayed as 1,0
	Come back to our program Here we get 1 and here we get as 0 Let us come back to our slides Let us summarize,
Summary	In this tutorial we learned, String library functions strlen() strcpy() strcmp() strncpy() and strncmp()
Slide 13 Assignment	As an assignemnt, Write a C Program to concatenate String best and String bus. Hint: strcat(char str1, char str2); Also explore the other functions in string library.
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 Number 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 [at] spoken hyphen tutorial dot org
Slide Number 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 the link shown below: http://spoken-tutorial.org\NMEICT-Intro
	This is Ashwini Patil from IIT Bombay. Thank you for joining.

Contributors and Content Editors

Ashwini