Teens' TString

#include <stdlib.h>
#include <string.h>

//我用了3天的时间来构想和编写这个类,大家使用一下,看看有什么

要改进的地方!并多多指点.

//最初编写这个类只是为了方便我编写字符串的程序,后来觉得发上

来给大家一起探讨可能会对我的
//学习有比较的的帮助  我也想结交编程方面的好友,我的

QQ:17160764
class TString
{
 public:
  TString():len(0),size(0),sp(0),error(0),pNeedFree(0){}
  TString(const char *Newchar);
 
          ~TString();
 public:
  void BigWrite();                 //全变成大写
  void LittleWrite();              //全变成小写
  const char *GetString()const{return sp;}//得到字符串的指针
  const int GetLen()const{return len;}  //得到字符串的长度
 public:
          //下面的用于字符串赋值
  TString & operator +=(const TString &copy);
  TString & operator +=(const char * Newchar);
          TString & operator =(const TString &copy);
          TString & operator =(const char * Newchar);
          //下面的都是用于字符串比较
  int operator ==(const char* cmp); 
  int operator ==(const TString &cmp);
  int operator !=(const char* cmp);
  int operator !=(const TString &cmp);
          int operator <(const char* cmp);
  int operator <(const TString &cmp);
  int operator >(const char* cmp);
  int operator >(const TString &cmp);
  int operator <=(const char* cmp);
  int operator <=(const TString &cmp);
  int operator >=(const char* cmp);
  int operator >=(const TString &cmp);
          //下面的用于连接字符串
  char* operator +(const char * cs);
  char* operator +(const TString & s1);
  char operator [](const int i);//这个用于提取某个字符

 public:
    int StrToInt(const char* interger);
    TString & ChangeLen(int NewLen);
 protected:
 
    int compare(const char* Cmpchar);
    int compare(const TString &Cmpchar)const;
    char * sp;  //存储字符串的
    int len;
    int size;
    int error;
    char * pNeedFree;//用于释放动态字符串
};

/////////////////////////////////////////////////////
TString::TString(const char *Newchar)
{
  pNeedFree=0;
    if(Newchar==NULL)
   {
     len=0;
     size=0;
     sp=NULL;
     error=0;
   }
 else
 {
   len=strlen(Newchar);
   size=len+1;
   sp=new char[size];
   if(sp!=NULL)
     strcpy(sp,Newchar);
  else
     error=(1);//out_of_memory);
 }
}

TString & TString::operator =(const TString &copy)
{
 if(this!=&copy)   //不能自赋值给自己
 {
   delete sp;
   if(copy.sp==NULL)
   {
      len=0;
      size=0;
      sp=0;
      error=0;
   }
   else
   {
     len=copy.len;
     size=len+1;
     sp=new char[size];
     if(sp!=NULL)
        strcpy(sp,copy.sp);
    else
        error=1;
   }
 }
   delete [] pNeedFree;
   return *this;
}

TString & TString::operator =(const char * Newchar)
{
   if(Newchar==NULL)
   {
       len=0;
       size=0;
       sp=NULL;
       error=0;
   }
  else
  {
     len=strlen(Newchar);
     size=len+1;
     sp=new char[size];
     if(sp!=NULL)
         strcpy(sp,Newchar);
     else
          error=1;
 }
   delete [] pNeedFree;
   return *this;
}

TString::~TString()
{
   delete sp;
   sp=0;

}

char* TString::operator +(const char  *cs)
{
 
    char *Newchar=new char[this->len+strlen(cs)+1];
    if(Newchar!=NULL)strcpy(Newchar,this->sp);
    if(cs !=NULL)strcat(Newchar,cs);
    pNeedFree=Newchar;
    return Newchar;

}

char* TString:: operator +(const TString & s1)
{
   char * Newchar=new char[s1.len+this->len+1];
   if(Newchar!=NULL)strcpy(Newchar,this->sp);
   if(s1.sp !=NULL)strcat(Newchar,s1.sp);
   pNeedFree=Newchar;
   return Newchar;
}

int TString::StrToInt(const char* interger)
{
 
    int i=0;
    i=atoi(interger);
    return i;

}

TString &TString:: operator +=(const char * Newchar)
{
    *this=ChangeLen(len+strlen(Newchar));
     strcat(sp,Newchar);
     return *this;
}

TString &TString:: operator +=(const TString &s1)
{
   *this=ChangeLen(len+s1.len);
   strcat(sp,s1.sp);
   return *this;
}

TString &TString:: ChangeLen(int NewLen)
{

   char *temp=new char[size];
   strcpy(temp,sp);
   len=NewLen; 
   size=len+1;
    if(sp!=NULL)delete sp;
    sp=new char[size];
    strcpy(sp,temp);
    delete temp;
    return *this;

}

char TString:: operator [](const int i)
{
    if(i<0)
 {
  error=2;
  return sp[0];
    }
    if(i>len)
 {
     error=2;
  return sp[len];
 }
    else
     return sp[i];
}

void TString::BigWrite()
{
   strupr(sp);
}

void TString::LittleWrite()
{
    strlwr(sp);
}

//////////////////////////////////////////////////
int TString::compare(const char* Cmpchar)
{
     return strcmp(sp,Cmpchar);
}

int TString::compare(const TString &Cmpchar)const
{
 return strcmp(sp,Cmpchar.sp);
}

int TString::operator ==(const char* cmp)
{
    return compare(cmp)==0;
}

int TString::operator ==(const TString& cmp)
{
    return compare(cmp)==0;
}

int TString::operator !=(const char* cmp)
{
    return compare(cmp)!=0;
}

int TString::operator !=(const TString &cmp)
{
 return compare(cmp)!=0;
}

int TString::operator <(const char* cmp)
{
 return compare(cmp)<0;
}

int TString::operator <(const TString &cmp)
{
 return compare(cmp)<0;
}

int TString::operator >(const char* cmp)
{
 return compare(cmp)>0;
}

int TString::operator >(const TString &cmp)
{
 return compare(cmp)>0;
}

int TString::operator <=(const char* cmp)
{
 return compare(cmp)<=0;
}

int TString::operator <=(const TString &cmp)
{
 return compare(cmp)<=0;
}

int TString::operator >=(const char* cmp)
{
 return compare(cmp)>=0;
}

int TString::operator >=(const TString &cmp)
{
 return compare(cmp)>=0;
}

//这个类还差一个错误处理,有时间我会添加上去
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