This document discusses strings in C programming. It explains that a string in C is an array of characters that ends with a null character. Common string functions like strcpy(), strcat(), strcmp() are presented for copying, concatenating, and comparing strings. The document also discusses declaring and initializing string variables, storing strings in memory, input/output of strings, and justification of strings using printf(). Library functions for manipulating strings from the string.h header file are described.

1. Lectures on Busy Bee Workshop 1
Busy Bee Workshop – Session VIBusy Bee Workshop – Session VI
This session Outline
String
String Manipulation Functions
String Programs

2. Lectures on Busy Bee Workshop 2
String in CString in C
Sequence of characters is called string.
In C, a string constant is a sequence of
characters enclosed in double quotes.
Examples:
“C Programming”
“SVN College”
“3/390 Nehru Street”
“45”

3. Lectures on Busy Bee Workshop 3
String in C - ImplementationString in C - Implementation
• C implements the stringstring data structure
using arrays of type char.
• We have already used the string
extensively.
– printf(“This program is terminated!n”);
– #define ERR_Message “Error!!”
• Since stringstring is an array, the declaration of
a string is the same as declaring a char
array.
– char string_var[30];
– char string_var[20] = “Initial value”;

4. Lectures on Busy Bee Workshop 4
String in C – Memory StorageString in C – Memory Storage
• The string is always ended with a nullnull
charactercharacter ‘0’‘0’.
• The characters after the null character are
ignored.
• e.g., char str[20] = “Initial value”;
n i t i a l v a l u e ? ? …I 00
[0] [13]

5. Lectures on Busy Bee Workshop 5
String in C – Arrays of StringsString in C – Arrays of Strings
• An array of strings is a two-dimensional
array of characters in which each row is one
string.
– char names[People][Length];
– char names[10][25];
– char month[5][10] = {“January”,
“February”, “March”, “April”, “May”};

6. Lectures on Busy Bee Workshop 6
String in C – Character vs. StringString in C – Character vs. String

7. Lectures on Busy Bee Workshop 7
String in C – Input/OutputString in C – Input/Output
• The placeholder %s%s is used to represent
string arguments in printf and scanf.
• Example:
char message1[12] = "Hello world";
printf(“%s”,message1);
message1:
char message2[12];
scanf(“%s”,message2); // type "Hello" as input
message2:
H e l l o w o r l d 0
H e l l o 0 ? ? ? ? ? ?

8. Lectures on Busy Bee Workshop 8
String in C – Right and Left Justification of StringsString in C – Right and Left Justification of Strings
• The string can be right-justified by placing a
positive number in the placeholder.
– printf(“%8s%8s”, str);
• The string can be left-justified by placing a
negative number in the placeholder.
– Printf(“%-8s%-8s”, str);

9. Lectures on Busy Bee Workshop 9
String in C – Example programString in C – Example program

10. Lectures on Busy Bee Workshop 10
String in C – Library FunctionsString in C – Library Functions
• The string can not be copied by the
assignment operator ‘=’.
– e..g, “str = “Test String”” is not valid.
• C provides string manipulating
functions in the “string.h” library.
– The list of these functions can be found in the next slide.

11. Lectures on Busy Bee Workshop 11
String in C – Library FunctionsString in C – Library Functions
Function Purpose Example
strcpy Makes a copy of a string strcpy(s1, “Hi”);
strcat Appends a string to the
end of another string
strcat(s1, “more”);
strcmp Compare two strings
alphabetically
strcmp(s1, “Hu”);
strlen Returns the number of
characters in a string
strlen(“Hi”) returns
2.
strtok Breaks a string into
tokens by delimiters.
strtok(“Hi, Chao”, “ ,”);

12. Lectures on Busy Bee Workshop 12
String in C – Library FunctionsString in C – Library Functions
Function Purpose Example
Strncpy Copy the specified
number of characters
strncpy(s1,
“SVN”,2);
Strncmp Compare two string upto
given n character
strncmp(“mo”,
“more”,2);
Stricmp Compare two strings
alphabetically without case
sensitivity.
stricmp(“hu”, “Hu”);
strlwr Converts string to all
lowercase
strlwr(“Hi”) returns
hi.
strupr Converts s to all
uppercase
strupr(“Hi”);

13. Lectures on Busy Bee Workshop 13
String in C – Library FunctionsString in C – Library Functions
Function Purpose Example
Strncat Appends a string to the
end of another string up
to n characters
strncat(s1,
“more”,2);
Strrev Reverses all characters
in s1 (except for the
terminating null)
strrev(s1, “more”);

14. Lectures on Busy Bee Workshop 14
String in C – Example program (Library Function)String in C – Example program (Library Function)