C++ LANGUAGE C-STYLE CHARACTER STRING

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C++ LANGUAGE C-STYLE CHARACTER STRING

C++ provides following two types of string representations: 

• The C-style character string. 

• The string class type introduced with Standard C++. 



The C-Style Character String 


The C-style character string originated within the C language and 
continues to be supported within C++. This string is actually a 
one-dimensional array of characters which is terminated by a null 
character '\0'. Thus a null-terminated string contains the characters 
that comprise the string followed by a null. 

The following declaration and initialization create a string 
consisting of the word "Hello". To hold the null character at 
the end of the array, the size of the character array containing 
the string is one more than the number of characters in the word "Hello." 

char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'}; 

If you follow the rule of array initialization, then you 
can write the above statement as follows: 

char greeting[] = "Hello"; 

Following is the memory presentation of above defined string in C/C++: 
 
Actually, you do not place the null character at the end of a string 
constant. The C++ compiler automatically places the '\0' at the end 
of the string when it initializes the array. Let us try to print 
above-mentioned string: 

#include <iostream> 

 
17. STRINGS 
using namespace std; 
 
int main () 
{ 
   char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'}; 
 
   cout << "Greeting message: "; 
   cout << greeting << endl; 
 
   return 0; 
} 
When the above code is compiled and executed, it produces the following result: 
Greeting message: Hello 
C++ supports a wide range of functions that manipulate null-terminated strings: 



S.N.                               Function & Purpose 


1  strcpy(s1, s2);              Copies string s2 into string s1. 

2  strcat(s1, s2);              Concatenates string s2 onto the end of string s1. 

3  strlen(s1);                  Returns the length of string s1. 

4  strcmp(s1, s2);              Returns 0 if s1 and s2 are the same; 
                                     less than 0 if s1<s2; greater than 0 if s1>s2. 
5  strchr(s1, ch);              Returns a pointer to the first 
                                     occurrence of character ch in string s1. 
6  strstr(s1, s2);              Returns a pointer to the first 
                                     occurrence of string s2 in string s1. 


Following example makes use of few of the above-mentioned functions: 
#include <iostream> 
#include <cstring> 
 
using namespace std; 
 
int main () 
{ 
   char str1[10] = "Hello"; 
   char str2[10] = "World"; 
   char str3[10]; 
   int  len ; 
 
   // copy str1 into str3 
   strcpy( str3, str1); 
   cout << "strcpy( str3, str1) : " << str3 << endl; 
 
   // concatenates str1 and str2 
   strcat( str1, str2); 
   cout << "strcat( str1, str2): " << str1 << endl; 
 
   // total lenghth of str1 after concatenation 
   len = strlen(str1); 
   cout << "strlen(str1) : " << len << endl; 
 
   return 0; 
} 
When the above code is compiled and executed, 
it produces result something as follows: 

strcpy( str3, str1) : Hello 
strcat( str1, str2): HelloWorld 
strlen(str1) : 10