string2.h

我学习C++ Primer Plus过程中写下的课后作业的编程代码

// string2.h -- fixed and augmented string class definition
#include <iostream>
using std::ostream;
using std::istream;

#ifndef STRING2_H_
#define STRING2_H_
class String
{
private:
	char * str;		// pointer to string
	size_t len;	    // length of string
	static const int CINLIM;	// cin input limit
public:
	// constructors and other methods
	String();
	String(const char * s);	    // constructor
	String(const String & s);	// copy constructor
	~String();
	size_t length()const { return len; }
	void stringlow();			// string change to lower
	void stringup();			// string change to upper
	int has(const char & c)const;

	// overload operator methods
	String & operator= (const String & s);
	String & operator= (const char * s);
	char & operator[] (int i);
	const char & operator[] (int i)const;
	String operator + (const String & st);
	String operator + (const char * st);


	// overload operator friends
	friend bool operator< (const String &st1, const String &st2);
	friend bool operator> (const String &st1, const String &st2);
	friend bool operator==(const String &st1, const String &st2);
	friend ostream & operator<< (ostream & os, const String & st );
	friend istream & operator>> (istream & is, String & st);
	friend String operator + (const char *  st1, const String & st2);
};
#endif