Strings in C++, Strings theory and concepts in C++

String

: A string is a sequence of characte that is treated as a single data item.

->

Functions used in string:-

   1. scanf() : It is a input function can be used with "%s" format specification to read in a string of character.
                   Example:
                             char address[10]
                             scanf("%s", address);
   2. getchar(): Use of this function to read single character from the input and place them in to character array.
                   Example:
                             char ch;
                             ch = getchar();
      'getchar' function has no parameters.
 
   3. gets() : It is a library function available in the <stdio.h> header file2  is used to read character in to string from the keyboard.
            This is a simple function wiyh one  string parameter.
                         
                              gets(str)
                   Example:
                             char line [80];
                             gets (line);
                             printf("%s", line);
 
   4. printf() : Used this function with "%s" format to print string to the screen.
                 
                   Example:
                             printf("%s", name);

   5. putchar() : This function is ysed to write character to the screen. And can use this function repeatedly to output a string
                  of character stored in an array using a loop.
                   ->Function putchar requires one parameter.
                   Example:
                             char name[6] = "PARIS";
                             for (i=0; i<5; i++)
                                  putchar(name[i]);
 
   6. puts() : This function is used for printing string values is to use the function 'puts' declared in the header file
               <stdio.h>.
               This is a one parameter function.
                             puts(str);
 
                                           

String-Handling Functions:

   1. strcat() : This functon join two string together. It takes the following form:
                             strcat(string1 , string2);

   2. strcmp()  : The strcmp function compares two strings identified by the arguments and hae the value 0 if they
                  are equal.
                             strcmp(string1 , string2);

   3. strcpy() : The strcpy function works almost like a string-assignment operator i.e is used copy second string in to
                 first string. It take forms :
                           
                             strcpy(string1 , string2);

   4. strlen() : The strlen function is used for count(count length of string) and returns the number of character in a
                 string. It takes form:
                         
                             n = strlen(string);
                         where n is a integer variable , which recieve the value of the length of the string.
                 The counting ends at the first null chartacter.

Other String Function:

   1. strncpy : This function copies only the left-most n characters of the surce string to the terget string variable.
                This is the three-parameter function and is invoked as follows:
                             strncpy(s1, s2, 5);
 
   2. strncmp : A variation of the function strcmp is the strncmp. This function has three-parameters as like:
                             strncmp(s1, s2, n);
                this compares the left-most n character of s1 to s2 and returns.
                (a) 0 if they are equal;
                (b) negative number, if s1 substring is less then s2;
                (c) positive number, otherwise.

   3. strncat : This is another concatenation function tht takes three parameter as shown below:
                       
                             strncat(s1, s2, n);
                this call will concatenate the left-most n character of s2 to the end of s1.

   4. strstr :  It is a two parameter function that can be used to locate sub-string in a string. This takes the forms:
         
                             strstr (s1, s2);            
                             strstr (s1, "ABC");