Strings

 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.

 Ex:

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

 the above statement can also be written as follows –

 char greeting[] = "Hello";

 C++ supports a wide range of functions that manipulate null-terminated strings –

 

Sr.No	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.

 

#include <iostream.h>

#include <cstring.h>

 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;

}

 

The String Class in C++

 The standard C++ library provides a string class type that supports all the operations mentioned above, additionally much more functionality.

 #include <iostream.h>

#include <string.h>

int main ( )

{

   string str1 = "Hello";

   string str2 = "World";

   string str3;

   int  len ;

    // copy str1 into str3

   str3 = str1;

   cout << "str3 : " << str3 << endl;

    // concatenates str1 and str2

   str3 = str1 + str2;

   cout << "str1 + str2 : " << str3 << endl;

    // total length of str3 after concatenation

   len = str3.size();

   cout << "str3.size() :  " << len << endl;

    return 0;

}