std::string

General Description

A std::string is an type in C++ used to represent a sequence of char types.

Include file

You can use the std::string class by including the string system include file with the statement

// include C++ std::string
#include <string>

Note that

// include old C-style strings
#include <string.h>

is completely different.

Namespace issues

You can use the full name std::string, or say

using namespace std;

This allows the shorter string name to work as well.

Basic Uses

A string can be assigned or compared to other strings, including literal strings inside double quotes. Here is a program which illustrates these basic uses:

// include C++ std::string
#include <string> 

// include basic stream input and output features
#include <iostream>

// allow string instead of std::string
using namespace std;

int main()
{
   string a;  // a is initally empty
   string b="bob";

   // report current values of a and b
   cout << "a=\"" << a << "\"" << endl;
   cout << "b=\"" << b << "\"" << endl;

   a = b;     // a is a copy of b now.
   b = "don";

   // report current values of a and b
   cout << "a=\"" << a << "\"" << endl;
   cout << "b=\"" << b << "\"" << endl;

   // the length() method gives back a
   // string's length:

   cout << "a is " << a.length() << " long" << endl;   
   cout << "b is " << b.length() << " long" << endl;
   

   // the + operator concatenates strings

   a = b + "ny";
   cout << "a=\"" << a << "\"" << endl;

   // the append() method appends to the string
   
   a.append(" and marie"); // same as: a = a + " and marie";
   cout << "a=\"" << a << "\"" << endl;

   // the index operator [] gives access to the individual
   // chars that make up the string.
   
   cout << "The first char of a is " << a[0] << endl;
   cout << "The last char of a is " << a[a.length()-1] << endl;

   // The relational operators are defined for string objects.

   a = "bob";
   b = "Bob";

   if (a == b) {
      cout << "a == b is true" << endl;
   } else {
      cout << "a == b is false" << endl;
   }

   return 0;
}