C – String

• C Strings are nothing but array of characters ended with null character (‘\0’).
• This null character indicates the end of the string.
• Strings are always enclosed by double quotes. Whereas, character is enclosed by single quotes in C.

Example for C string:

• char string[20] = { ‘f’ , ’r’ , ‘e’ , ‘s’ , ‘h’ , ‘2’ , ‘r’ , ‘e’ , ‘f’ , ’r’ , ‘e’ , ‘s’ , ‘h’ , ‘\0’}; (or)
• char string[20] = “fresh2refresh”; (or)
• char string []    = “fresh2refresh”;

• Difference between above declarations are, when we declare char as “string[20]“, 20 bytes of memory space is allocated for holding the string value.
• When we declare char as “string[]“, memory space will be allocated as per the requirement during execution of the program.

Example program for C string:

#include <stdio.h>

int main ()
{
   char string[20] = "netajimahavidyalayacompscmag.blogspot.in";

   printf("The string is : %s \n", string );
   return 0;
}

Output:

The string is : netajimahavidyalayacompscmag.blogspot.in

C String functions:

• String.h header file supports all the string functions in C language. All the string functions are given below.

S.no	String functions	Description
1	strcat ( )	Concatenates str2 at the end of str1.
2	strncat ( )	appends a portion of string to another
3	strcpy ( )	Copies str2 into str1
4	strncpy ( )	copies given number of characters of one string to another
5	strlen ( )	gives the length of str1.
6	strcmp ( )	Returns 0 if str1 is same as str2. Returns <0 if strl < str2. Returns >0 if str1 > str2.
7	strcmpi_(.)	Same as strcmp() function. But, this function negotiates case.  “A” and “a” are treated as same.
8	strchr ( )	Returns pointer to first occurrence of char in str1.
9	strrchr ( )	last occurrence of given character in a string is found
10	strstr ( )	Returns pointer to first occurrence of str2 in str1.
11	strrstr ( )	Returns pointer to last occurrence of str2 in str1.
12	strdup ( )	duplicates the string
13	strlwr ( )	converts string to lowercase
14	strupr ( )	converts string to uppercase
15	strrev ( )	reverses the given string
16	strset ( )	sets all character in a string to given character
17	strnset ( )	It sets the portion of characters in a string to given character
18	strtok ( )	tokenizing given string using delimiter