String

                                                                                  String

There is no separate data type for string in C , they are treated as array of characters. A character array is a string if it ends with a null character  (‘\0’). This  null character is an escape sequence with ASCII value 0  and is different from the ASCII  character ‘0’.

String are generally  used to store and manipulate data in text form like word or sentence.

String Constant

A string constant is a sequence of character enclosed in double quotes and is also called a literal . ”double quote are not a part of the string.e.g: “TAJ” “deep”.

String Liberary Function:

There are several library functions used to manipulate strings and the prototype for these functions are in header file string.h  most commonly used string function like: strlen(), strcpy(),strcmp(),strcat().

1.       Strlen()

Declaration: size_x strlen(char const *string); This function returns the length of the string i.e the number of character in the string excluding the terminating null character. Program to understand strlen(): #include<stdio.h> #include<string.h> Int main(void)  {   Char str[50];   Printf(“enter the string:”);   Gets(str);   Printf(“Length of string:%d\n”,strlen(str));  Return 0; }

2.       Strcpy

Declaration: char * strcpy(char *s1 , const char *s2); This function is used for copying one string to another string. Program to understand strcpy(): #include<stdio.h> #include<string.h> Int main(void)  {   Char str[50],str1[50];   Printf(“enter the string:”);   Gets(str);  Strcpy(str1,str);   Printf(“first string:%s\n second string:%s\n”,str,str1);  Return 0; }

3.       Strcmp()

Declaration: int strcmp(char* s1,char *s2); This function is used for lexicographic comparison of two strings. If the two string match,strcmp() returns a vlue 0 otherwise it returns a non-zero. It compares the string character by character and the comparison stops when either the end of string is reached or the corresponding characters in the two strings are not same. Strcmp(s1,s2) return a value: <0   when s1 <s2 =0    s1==s2 >0   s1>s2 /* program to understand the work of strcmp() function*/ #include<stdio.h> #include<string.h> Main(void)  {    Char str1[90],str2[90]; Printf(“enter two strings :”);  Gets(str1);  Gets(str2);  If((strcmp(str1,str2))==0)   Printf(“strings are same\n”);  Else   Printf(“strings are not same\n”);  Return 0; } Output: Enter two strings: Deepak                                                 Kumar Strings are not same.

4.       Strcat

Declaration : char* strcat(char*str1,const char*str2) This function is used to append a copy  of a string at the end of other string.e.g if first string is “Cprogram” and second string is “stores “ then the output will come as Cprogramstores /* Program to understand strcat() function*/ #include<stdio.h> #include<string.h> int main(void) {    char str1[20],str2[20];    printf(“enter two string:”);    gets(str1);    gets(str2);   strcat(str1,str2);  printf(“%s\n”,str1);  return 0; }