CS107: C++ Programming

C and C++ do not have a native string data type.

Instead they rely on a null terminated char array, and are initialised in C like so:

char chArr[] = “My new house” ;
char *ptrArr = “You should see my new house” ;

C++ has an alternative method of handling strings that uses the string class, thus creating a string object.

Requires the #include <string> preprocessor directive, allowing string to be used like any other data type.

Part of the std namespace, and therefore also requires the using namespace std; preprocessor directive.

Declared / defined by simply using the string keyword:

  
string myString ;  //declaration

myString = “Hip Priests and Kamerads” ;  //definition

string yourString = “This Nation’s Saving Grace” ;  //initialisation

string cppString(“C++ string text goes in here”) ; //initialisation
        

The last example above sends a double quoted list of characters as the parameter to the string class, to create the string object containing the quoted characters.

Example using the .length() method of the string class:

#include <iostream>
#include <string>
using namespace std;
 
int main () {
 
    string myString ;
 
    myString = "The amazing Spiderman" ;
 
  
     for (int i = 0 ; i < myString.length() ; i++) {
 
        cout << "Array element ["<< i <<"] contains: " << myString[i] << endl ;
    }
  
     cout << myString << endl ;
 
    return 0;
}

Compile & Run:

Array element [0] contains: T
Array element [1] contains: h
Array element [2] contains: e
Array element [3] contains:
Array element [4] contains: a
Array element [5] contains: m
Array element [6] contains: a
Array element [7] contains: z
Array element [8] contains: i
Array element [9] contains: n
Array element [10] contains: g
Array element [11] contains:
Array element [12] contains: S
Array element [13] contains: p
Array element [14] contains: i
Array element [15] contains: d
Array element [16] contains: e
Array element [17] contains: r
Array element [18] contains: m
Array element [19] contains: a
Array element [20] contains: n
 
The amazing Spiderman

Example using the iterator, begin() and end() methods of the string class, and then dereferencing a pointer to access the individual characters within the string object:

C string class methods

#include <iostream>
#include <string>
using namespace std;
 
int main () {
 
    string yourString = "The Green Goblin" ;
 
    int i = 0 ;
 
  
         for (string::iterator it = yourString.begin() ; it < yourString.end() ; ++it, i++) {
 
        cout << "Array element ["<< i <<"] contains: " << *it << endl ;
  
         }
        
    cout << yourString << endl ;
 
    string cppString = "string" ;
 
    return 0;
}

Compile & Run:

Array element [0] contains: T
Array element [1] contains: h
Array element [2] contains: e
Array element [3] contains:
Array element [4] contains: G
Array element [5] contains: r
Array element [6] contains: e
Array element [7] contains: e
Array element [8] contains: n
Array element [9] contains:
Array element [10] contains: G
Array element [11] contains: o
Array element [12] contains: b
Array element [13] contains: l
Array element [14] contains: i
Array element [15] contains: n

The Green Goblin

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Source: Derrick Robinson, http://web.archive.org/web/20160820094657/http://cpp.tech-academy.co.uk/c-string-class/
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