cppreference.com > C++ Strings > String operators String operators Syntax:
      #include <string>
      bool operator==(const string& c1, const string& c2);
      bool operator!=(const string& c1, const string& c2);
      bool operator<(const string& c1, const string& c2);
      bool operator>(const string& c1, const string& c2);
      bool operator<=(const string& c1, const string& c2);
      bool operator>=(const string& c1, const string& c2);
      string operator+(const string& s1, const string& s2 );
      string operator+(const char* s, const string& s2 );
      string operator+( char c, const string& s2 );
      string operator+( const string& s1, const char* s );
      string operator+( const string& s1, char c );
      ostream& operator<<( ostream& os, const string& s );
      istream& operator>>( istream& is, string& s );
      string& operator=( const string& s );
      string& operator=( const char* s );
      string& operator=( char ch );
      char& operator[]( size_type index );
C++ strings can be compared and assigned with the standard comparison operators: ==, !=, <=, >=, <, >, and =. Performing a comparison or assigning one string to another takes linear time. Two strings are equal if:
      1. Their size is the same, and
      2. Each member in location i in one string is equal to the the member in location i in the other string.
Comparisons among strings are done lexicographically. In addition to these normal (C++ Multimaps) Container operators, strings can also be concatenated with the + operator and fed to the C++ I/O stream classes with the << and >> operators. For example, the following code concatenates two strings and displays the result:
     string s1 = "Now is the time...";
     string s2 = "for all good men...";
     string s3 = s1 + s2;
     cout << "s3 is " << s3 << endl;
Furthermore, strings can be assigned values that are other strings, character arrays, or even single characters. The following code is perfectly valid:
     char ch = 'N';
     string s = ch;
Individual characters of a string can be examined with the [] operator, which runs in constant time. Related topics: (C++ Multimaps) Container operators c_str compare data