Strncat s3 s1 6 happy strcat s3 s1 happy happy new

strncat( s3, s1, 6 ) = Happy
strcat( s3, s1 ) = Happy Happy New Year
Quick yak:
Ask students
to print their
names as:
Ankur Sharma
Sharma Ankur
Ankur S.
A. Sharma

©LPU CSE101 C Programming
Comparison Functions of the
String Handling Library
•
Comparing strings
–
Computer compares numeric ASCII codes of
characters in string
–
strcmp()
Compares its first string argument with
its second string argument, character by character.
–
Function
strncmp()
does not compare characters
following a null character in a string.

©LPU CSE101 C Programming
strcmp()
int strcmp( const char *s1, const char *s2 );
–
Compares string
s1
to
s2
–
Returns
•
a negative number if
s1 < s2
,
•
zero if
s1 == s2
•
a positive number if
s1 > s2
Quick yak:
Comparison of
strings:
Meghalaya
Manipur
To be
discussed

©LPU CSE101 C Programming
strncmp()
int strncmp( const char *s1, const char *s2,
int
n);
–
Compares up to
n
characters of string
s1
to
s2
•
a negative number if
s1 < s2
,
•
zero if
s1 == s2
•
a positive number if
s1 > s2

©LPU CSE101 C Programming
Example Code
This program
demonstrates
string
comparison
functions:
strcmp() and
strncmp()

©LPU CSE101 C Programming
Output
s1 = Happy New Year
s2 = Happy New Year
s3 = Happy Holidays
strcmp(s1, s2) = 0
strcmp(s1, s3) = 1
strcmp(s3, s1) = -1
strncmp(s1, s3, 6) = 0
strncmp(s1, s3, 7) = 1
strncmp(s3, s1, 7) = -1
Quick yak:
Students to
create a
friendsh
ip
game:
Based on the
score out of
-1,0,1 of frst
names of two
people….

©LPU CSE101 C Programming
Determining the length of string
strlen()
•
Function
strlen in #include<string.h>
•
Function strlen() takes a string as an
argument and returns the number of
characters in the string
–
the terminating null character is not included in
the length

©LPU CSE101 C Programming
#include <stdio.h>
#include <string.h>
void main()
{
/* initialize 3 char pointers */
const char *string1 =
"abcdefghijklmnopqrstuvwxyz";
const char *string2 = "four";
const char *string3 = "Boston";
printf( "%s\"%s\"%s%d\n%s\"%s\"%s%d\n
%s\"%s\"%s%d\n" ,
"The length of “ ,string1, "is" ,
strlen(string1) ,
"The length of “ ,string2, ”is“ ,
strlen(string2) ,
"The length of “ ,string3, ”is“ ,
strlen(string3) );
} /* end main */
Program
demonstrates
string length
function strlen()

The length of "abcdefghijklmnopqrstuvwxyz" is 26
The length of "four" is 4
The length of "Boston" is 6

©LPU CSE101 C Programming
[email protected]
Next Lecture
Mining different types of data
from string …??
String conversion functions