习作！

发布: 2007-7-01 20:40 | 作者: admin | 来源: | 查看: 11次 | 进入软件测试论坛讨论

C++这个动东东以前看了始终没有写过代码，昨天看了今天花了一天时间，调了一个小类，让大家指点指点：

/*********************** tstring.h **********************************

#ifndef TSTRING_H
#define TSTRING_H

#define NULL    0
#define TRUE    1
#define FALSE    0

typedef long BOOL;

typedef unsigned long DWORD;

class TSTRING
{
public:

TSTRING(const char * pStr = NULL);
~TSTRING();

void SetNewString(const char * pStr = NULL);
char * GetString(void);
DWORD GetStringLen(void);

void Print(void);

/**********************************************************
**There are some side effects in assignment(=) overloading
** with plus(+) overloading case(TSTRING &, TSTRING &).
***********************************************************/
& operator = (const char * pStr);

friend TSTRING & operator + (TSTRING & oStr, const char * pStr);
friend TSTRING & operator + (const char * pStr, TSTRING & oStr);
friend TSTRING & operator + (TSTRING & oStr1, TSTRING & oStr2);

protected:

BOOL bNewAlloc; // Indicate whether memory is allocated
char * pHeader; // Indicate the first character of the string
DWORD dLen; // Indicate the number of characters

private:

char cNull; // Represent the string when it is null.
};

#endif

/******************* tstring.cpp **************************************

#include <malloc.h>
#include <string.h>
#include <iostream>

using namespace std;

#include "tstring.h"

TSTRING :: TSTRING(const char * pStr)
{
if (pStr == NULL) {
dLen = 0;

// Set pHeaer to point a null string
cNull = 0;
pHeader = &cNull;

  bNewAlloc = FALSE;
}
else {
  dLen = strlen(pStr);
  pHeader = (char *) malloc(dLen + 1);
  strcpy(pHeader, pStr);

  bNewAlloc = TRUE;
}
}

TSTRING :: ~TSTRING()
{
// If the memory used by the string is allocated originally
// by compiler, MUST NOT free it, or cause a exception!
if (bNewAlloc)
free(pHeader);

}

void TSTRING :: SetNewString(const char * pStr)
{
long lLen = strlen(pStr);

// If the space is exactly enough, NO NEED to allocate memory.
if (dLen != lLen) {
  if (bNewAlloc)
   free(pHeader);
  pHeader = (char *) malloc(lLen + 1);
  dLen = lLen;
  bNewAlloc = TRUE;
}
strcpy(pHeader, pStr);
}

char * TSTRING :: GetString(void)
{
return pHeader;
}

DWORD TSTRING :: GetStringLen(void)
{
return dLen;
}

void TSTRING :: Print(void)
{
cout << pHeader;
}

/*
TSTRING & TSTRING :: operator = (const char * pStr)
{
if (bNewAlloc)
free(pHeader);
dLen = strlen(pStr);
pHeader = (char *) malloc(dLen + 1);
strcpy(pHeader, pStr);

return * this;
}
*/

TSTRING & operator + (TSTRING & oStr, const char * pStr)
{
TSTRING *pNewStr = new TSTRING;

long lLen;

lLen = oStr.dLen + strlen(pStr);
pNewStr->pHeader = (char *) malloc(lLen + 1);

strcpy(pNewStr->pHeader, oStr.pHeader);
strcpy(pNewStr->pHeader + oStr.dLen, pStr);

pNewStr->bNewAlloc = TRUE;
pNewStr->dLen = lLen;

return * pNewStr;
}

TSTRING & operator + (const char * pStr, TSTRING & oStr)
{

TSTRING *pNewStr = new TSTRING;

long lLen;

lLen = strlen(pStr);
pNewStr->pHeader = (char *) malloc(lLen + oStr.dLen + 1);

strcpy(pNewStr->pHeader, pStr);
strcpy(pNewStr->pHeader + lLen, oStr.pHeader);

pNewStr->bNewAlloc = TRUE;
pNewStr->dLen = lLen + oStr.dLen;

return * pNewStr;
}

TSTRING & operator + (TSTRING & oStr1, TSTRING & oStr2)
{

TSTRING *pNewStr = new TSTRING;

pNewStr->dLen = oStr1.dLen + oStr2.dLen;
pNewStr->pHeader = (char *) malloc(pNewStr->dLen + 1);

strcpy(pNewStr->pHeader, oStr1.pHeader);
strcpy(pNewStr->pHeader + oStr1.dLen, oStr2.pHeader);

pNewStr->bNewAlloc = TRUE;

return * pNewStr;
}

/************************* learn.cpp (including main entry function) ************

#include "tstring.h"

int main(int argc, char * argv[])
{

TSTRING str1("Original string!\n");
str1.Print();

str1.SetNewString("New string!");
str1.Print();

TSTRING & str2 = str1;

str2 = "pre_" + str1 + "_post!";
str2.Print();

return 0;
}