String notes

STRINGS
WHAT IS STRING
The string can be defined as the one-dimensional array of characters terminated by a null ('0').
This null character indicates the end of the string.
Each character in the array occupies one byte of memory, and the last character must always be
0. The termination character ('0') is important in a string since it is the only way to identify
where the string ends.
Strings are always enclosed by double quotes. Whereas, character is enclosed by single quotes in
C.
Example: ‘Kedia’, “Kedia”
DECLARING AND INITIALIZING STRING
There are two ways to declare and initializing a string in c language.
1. By char array
2. By string literal
Declaring String
Syntax: Datatype string_variable_name [array_Size];
Example: char s[5];
When we declare string array with size 5 then it will create sequential memory.
As we know, array index starts from 0, so it will be represented as in the figure given below.
Initializing String:
Initializing means while declaring char array if we assign elements or literals.
Syntax: Datatype string_variable_name [array_size] ={characters};
Example: char s[5]= {‘K’,’E’,’D’,’I’,’A’,’0’};
Prasadu peddi R.G. Kedia College of commerce

What is NULL Char “0”?
'0' represents the end of the string. It is also referred as String terminator & Null Character.
Declaring String by string Literal:
char ch[]="RGKEDIA";
Difference between char array and string literal:
There is main difference between char array and String literal.
We need to add the null character '0' at the end of the array by ourself whereas, it is
appended internally by the compiler in the case of the string literal.
String Example in C
Let's see a simple example where a string is declared and being printed. The '%s' is used as
a format specifier for the string in c language.
#include<stdio.h>
#include <string.h>
Void main()
{
char str1[8]={'R', 'G', 'K', 'E', 'D', 'I', 'A', '0'};
char str2[8] ="RGKEDIA";
printf("Char Array Value is: %sn", str1);
printf("String Literal Value is: %sn", str2);
}
READING AND WRITING STRINGS
Accepting string as the input:
Till now, we have used scanf to accept the input from the user. However, it can also be used
in the case of strings but with a different scenario. The '%s' is used as a format specifier for
the string in c language. In Scanf() for reading integer and float values format specifier %d,
%f and “&” required where as for reading string & not required.
#include<stdio.h>
void main ()
{

char s[20];
printf("Enter the string?");
scanf("%s",s);
printf("You entered %s",s);
}
Output1:
Enter the string?
Corona
You entered corona
Output2:
Enter the string?
Corona is a virus
You entered corona
Note: in output1, input string is ‘corona’ and it is displayed as it is where as in output2,
input is ‘corona is a virus’ but output is corona. It is clear from the output2 that, the Scanf
will not work for space separated strings.
The problem with the scanf function is that it never reads an entire string. It will halt the reading
process as soon as whitespace, suppose we give input as "B.COM First Year" then the scanf
function will never read an entire string as a whitespace character occurs between the two names.
The scanf function will only read B.COM and it ignores remaining strings.
gets() Function:
The gets() function is similar to scanf() function. In order to read a string contains spaces, we use
the gets() function. Gets ignores the whitespaces. It stops reading when a newline is reached (the
Enter key is pressed).
The gets() function enables the user to enter some characters followed by the enter key. All the
characters entered by the user get stored in a character array. The null character is added to the
array to make it a string. The gets() allows the user to enter the space-separated strings. It returns
the string entered by the user.
Reading string using gets():
#include<stdio.h>

void main ()
{
char s[30];
printf("Enter the string? ");
gets(s);
printf("You entered %s",s);
}
OUTPUT
Enter the string?
RG Kedia College
You entered RG Kedia College
puts() function
The puts() function is very much similar to printf() function. The puts() function is used to
print the string on the console which is previously read by using gets() or scanf() function.
The puts() function returns an integer value representing the number of characters being
printed on the console. The difference between printf and puts is printf display integer, float,
and char values where as puts used for only to display string.
#include<stdio.h>
#include <string.h>
void main()
{
char name[50];
printf("Enter string: ");
gets(name); //reads string from user
printf("Your string is: ");
puts(name); //displays string
}
OUTPUT
Enter string:
Corona virus disease also called COVID
Your string is: Corona virus disease also called COVID

STRING STANDARD FUNCTIONS
1) strlen(string_name) function is used to find the length of a character string.
It doesn't count null character '0'.
The strlen() function takes a string as an argument and returns its length. The returned
value is of type int.
It is defined in the <string.h> header file.
Example: int n;
char st[20] = “studnet”;
n = strlen(st);
#include<stdio.h>
#include <string.h>
int main()
{
Int len;
char ch[20]=”student”;
len=strlen(ch);
printf("Length of string is: %d",len);
return 0;
}
2) strcpy(destination, source) copies the contents of source string to destination string.
The strcpy() function copies the string to the another character array.
The strcpy() function is defined in the string.h header file.
strcpy ( str1, str2) – It copies contents of str2 into str1.
strcpy ( str2, str1) – It copies contents of str1 into str2.
#include<stdio.h>
#include <string.h>
int main()
{

char cp1[20]={'s’,’t’,’u’,’d’,’e’,’n’,’t’,’0’};
char cp2[20];
strcpy(cp2,cp1);
puts(cp2);
return 0;
}
3) strcat(first_string, second_string) concats or joins first string with second string. The
result of the string is stored in first string.
It takes two arguments, i.e, two strings or character arrays, and stores the resultant concatenated
string in the first string specified in the argument.
The strcat() function is defined in <string.h> header file.
#include <stdio.h>
#include <string.h>
int main()
{
char str1[] = "This is ", str2[] = "online class";
//concatenates str1 and str2 and resultant string is stored in str1.
strcat(str1,str2);
puts(str1);
puts(str2);
return 0;
}
output
This is online class
Online class

4) strcmp(first_string, second_string) compares the first string with second string. If both
strings are same, it returns 0.
strcmp( ) function is case sensitive. i.e., “A” and “a” are treated as different characters.
If length of string1 < string2, it returns < 0 value. If length of string1 > string2, it returns > 0
value.
It is defined in the string.h header file.
int n;
n = strcmp(city, town);
#include <stdio.h>
#include <string.h>
int main()
{
char str1[] = "abcd", str2[] = "abCd", str3[] = "abcd";
int result;
// comparing strings str1 and str2
result = strcmp(str1, str2);
printf("strcmp(str1, str2) = %dn", result);
// comparing strings str1 and str3
result = strcmp(str1, str3);
printf("strcmp(str1, str3) = %dn", result);
return 0;
}
OUTPUT
strcmp(str1, str2) = 32
strcmp(str1, str3) = 0

5) strrev(string) returns reverse string.
This function returns reverse of the given string.
#include<stdio.h>
#include <string.h>
int main(){
char str[20];
printf("Enter string: ");
gets(str);//reads string from console
puts(str);
printf("Reverse String is: %s",strrev(str));
return 0;
}
OUTPUT
Enter string: student
String is: student
Reverse String is: tneduts
6) strlwr(string) returns string characters in lowercase.
7) strupr(string)returns string characters in uppercase.

String notes

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