#include<iostream>
class String
{
friend ostream& operator<<( ostream &stream, String &obj);
public:
	String ( char *str); // конструктор
	~String () { delete []ptr; } // деструктор
private:
	int lenght;
	char *ptr;
};
String::String ( char *str ) // опис. конструктора
{
	if ( str == NULL || strlen(str) == 0 )
	{
		ptr = new char[1];
		ptr[0] = '\0';
		lenght = 0;
	}
	else
	{
		lenght = strlen(str);
		ptr = new char[lenght];
		for ( int i=0; i<lenght; i++)
			ptr[i] = '0';
		ptr[lenght] = '\0';
	}
}
int main()
{
// тут какой то код 
}
ostream& operator << (ostream &stream, String &obj)
{
// тут описание оператора ввода в поток.
}

friend ostream& operator<<( ostream &stream, String &obj);
error C2143: syntax error : missing ';' before '&'
error C2433: 'ostream' : 'friend' not permitted on data declarations
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
error C2061: syntax error : identifier 'ostream'
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
error C2805: binary 'operator <<' has too few parameters

friend ostream& operator << (ostream &stream, String &obj)
error C2143: syntax error : missing ';' before '&'
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
error C2086: 'int ostream' : redefinition
error C2065: 'stream' : undeclared identifier
error C2065: 'obj' : undeclared identifier
error C2275: 'String' : illegal use of this type as an expression
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
fatal error C1903: unable to recover from previous error(s); stopping compilation