C++ string实现

最近心血来潮，通过参考书目和网上资料，实现了下 C++ 标准库 std::string 的部分功能。

话不多说，直接上代码

#ifndef FBC_STL_STRING_HPP_
#define FBC_STL_STRING_HPP_

#include <string.h>

namespace fbcstd {
	
class String{
public:
	String();
	String(const char* str);
	String(const char* str, size_t n);
	String(const String &str);
	String(const String &str, size_t pos, size_t len = npos);
	String(size_t n, char c);
	~String();
	
	const char* c_str() const;
	size_t length() const;
	size_t size() const;
	
	char& operator [] (size_t pos);
	const char& operator [] (size_t pos) const;
	
	String& operator = (const String& str);
	String& operator = (const char* str);
	String& operator = (char c);
	String& operator += (const String& str);
	String& operator += (const char* str);
	String& operator += (char c);
	
	String& append(const String& str);
	String& append(const char* str);
	
	String& assign(const String& str);
	String& assign(const char* str);
	
	char& at(size_t pos);
	const char& at(size_t pos) const;
	
	void clear();
 
	int compare(const String& str) const;
	int compare(const char* s) const;
 
	const char* data() const;
	bool empty() const;
 
	static const size_t npos = -1;
	
private:
	size_t size_;
	char* buffer_;
};

inline String::String() {
	size_ = 0;
	buffer_ = new char[1];
	buffer_[0] = '';
}

inline String::String(const char *str) {
	size_ = strlen(str);
	buffer_ = new char[size_ + 1];
	strcpy(buffer_, str);
}

inline String::String(const String& str) {
	size_ = str.size_;
	buffer_ = new char[size_ + 1];
	strcpy(buffer_, str.buffer_);
}

inline String::String(const String &str, size_t pos, size_t len) {
	if(pos > str.size_) {
		size_ = 0;
		buffer_ = new char[1];
		buffer_[0] = '';
	}
	else {
		if(pos + len > str.size_) size_ = str.size_ - pos; 
		else size_ = len;
		buffer_ = new char[size_ + 1];
		for(size_t i; i < size_; i++){
			buffer_[i] = str[i + pos];		
			}
		buffer_[size_] = '';
	}
}

inline String::String(const char* str, size_t n) {
	if(strlen(str) < n) {
		size_ = strlen(str);
		buffer_ = new char[size_ +1];
		strcpy(buffer_, str);
	}
	else {
		size_ = n;
		buffer_ = new char[size_ +1];
		strncpy(buffer_, str, n);
	}
}

inline String::String(size_t n, char c) {
	size_ = n;
	buffer_ = new char[size_ + 1];
	memset(buffer_, c, n);
}

inline String::~String() {
	if(buffer_) delete[] buffer_;
	size_ = 0;
}


inline const char* String::c_str() const {
	return buffer_;
}

inline size_t String::length() const {
	return size_;
}

inline size_t String::size() const {
	return size_;
}


inline char& String::operator [] (size_t pos) {
	return buffer_[pos];
}

inline const char& String::operator [] (size_t pos) const {
	if(pos > size_) return '';
	return buffer_[pos];
}

inline String& String::operator = (const String& str) {
	if(this->size_ != 0){
		delete[] buffer_;
	}
	size_ = str.size_;
	buffer_ = new char[size_ + 1];
	strcpy(buffer_, str.c_str());
	return *this;
}

inline String& String::operator = (const char* str) {
	if(this->size_ != 0){
		delete[] buffer_;
	}
	size_ = strlen(str);
	buffer_ = new char[size_ + 1];
	strcpy(buffer_, str);
	return *this;
}

inline String& String::operator = (char c) {
	if(this->size_ != 0){
		delete[] buffer_;
	}
	size_ = 1;
	buffer_ = new char[size_ + 1];
	buffer_[0] = c;
	buffer_[size_] = '';
	return *this;
}

inline String& String::operator += (const String& str) {
	size_ += str.size_;
	char* data = new char[size_ + 1];
	strcpy(data, buffer_);
	strcat(data, str.buffer_);
	delete[] buffer_;
	buffer_ = data;
	return *this;
}

inline String& String::operator += (const char* str) {
	size_ += strlen(str);
	char* data = new char[size_ + 1];
	strcpy(data, buffer_);
	strcat(data, str);
	delete[] buffer_;
	buffer_ = data;
	return *this;
}

inline String& String::operator += (char c) {
	size_ += 1;
	char* data = new char[size_ + 1];
	strcpy(data, buffer_);
	strcat(data, &c);
	delete[] buffer_;
	buffer_ = data;
	return *this;
}

inline String& String::append(const String& str) {
	*this += str;
	return *this;
}

inline String& String::append(const char* str) {
	*this += str;
	return *this;
}


inline String& String::assign(const String& str) {
	*this = str;
	return *this;
}
	
inline String& String::assign(const char* str) {
	*this = str;
	return *this;
}

inline char& String::at(size_t pos) {
	return buffer_[pos];
}
	
inline const char& String::at(size_t pos) const {
	return buffer_[pos];
}

inline void String::clear() {
	if(buffer_) delete[] buffer_;
	size_ = 0;
	buffer_ = new char[1];
	buffer_[0] = '';
}

inline int String::compare(const String& str) const {
	return strcmp(buffer_, str.buffer_);
}
 
inline int String::compare(const char* s) const{
	return strcmp(buffer_, s);
}
 
inline const char* String::data() const {
	return buffer_;
}
	
inline bool String::empty() const {
	return (size_ == 0);
}


static inline String operator + (const String& lhs, const String& rhs)
{
	String str(lhs);
	str += rhs;
	return str;
}
 
static inline String operator + (const String& lhs, const char* rhs)
{
	String str(lhs);
	str += rhs;
	return str;
}
 
static inline String operator + (const char* lhs, const String& rhs)
{
	String str(lhs);
	str += rhs;
	return str;
}
 
static inline String operator + (const String& lhs, char rhs)
{
	String str(lhs);
	str += rhs;
	return str;
}
 
static inline String operator + (char lhs, const String& rhs)
{
	String str(&lhs);
	str += rhs;
	return str;
}
 
static inline bool operator == (const String& lhs, const String& rhs)
{
	return (lhs.compare(rhs) == 0);
}
 
static inline bool operator == (const char* lhs, const String& rhs)
{
	return (rhs.compare(lhs) == 0);
}
 
static inline bool operator == (const String& lhs, const char* rhs)
{
	return (lhs.compare(rhs) == 0);
}
 
static inline bool operator != (const String& lhs, const String& rhs)
{
	return (lhs.compare(rhs) != 0);
}
 
static inline bool operator != (const char* lhs, const String& rhs)
{
	return (rhs.compare(lhs) != 0);
}
 
static inline bool operator != (const String& lhs, const char* rhs)
{
	return (lhs.compare(rhs) != 0);
}
 
static inline bool operator < (const String& lhs, const String& rhs)
{
	return (lhs.compare(rhs) < 0);
}
 
static inline bool operator < (const char* lhs, const String& rhs)
{
	return (rhs.compare(lhs) >= 0);
}
 
static inline bool operator < (const String& lhs, const char* rhs)
{
	return (lhs.compare(rhs) < 0);
}
 
static inline bool operator <= (const String& lhs, const String& rhs)
{
	return (lhs.compare(rhs) <= 0);
}
 
static inline bool operator <= (const char* lhs, const String& rhs)
{
	return (rhs.compare(lhs) > 0);
}
 
static inline bool operator <= (const String& lhs, const char* rhs)
{
	return (lhs.compare(rhs) <= 0);
}
 
static inline bool operator > (const String& lhs, const String& rhs)
{
	return (lhs.compare(rhs) > 0);
}
 
static inline bool operator > (const char* lhs, const String& rhs)
{
	return (rhs.compare(lhs) <= 0);
}
 
static inline bool operator > (const String& lhs, const char* rhs)
{
	return (lhs.compare(rhs) > 0);
}
 
static inline bool operator >= (const String& lhs, const String& rhs)
{
	return (lhs.compare(rhs) >= 0);
}
 
static inline bool operator >= (const char* lhs, const String& rhs)
{
	return (rhs.compare(lhs) < 0);
}
 
static inline bool operator >= (const String& lhs, const char* rhs)
{
	return (lhs.compare(rhs) >= 0);
}

} // namespace fbcstd

#endif

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