use_str.cpp

最新推荐文章于 2024-03-22 23:16:36 发布

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#allocation #string #stream #delete #object #constructor

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name="google_ads_frame" marginwidth="0" marginheight="0" src="http://pagead2.googlesyndication.com/pagead/ads?client=ca-pub-5572165936844014&dt=1194442938015&lmt=1194190197&format=336x280_as&output=html&correlator=1194442937843&url=file%3A%2F%2F%2FC%3A%2FDocuments%2520and%2520Settings%2Flhh1%2F%E6%A1%8C%E9%9D%A2%2FCLanguage.htm&color_bg=FFFFFF&color_text=000000&color_link=000000&color_url=FFFFFF&color_border=FFFFFF&ad_type=text&ga_vid=583001034.1194442938&ga_sid=1194442938&ga_hid=1942779085&flash=9&u_h=768&u_w=1024&u_ah=740&u_aw=1024&u_cd=32&u_tz=480&u_java=true" frameborder="0" width="336" scrolling="no" height="280" allowtransparency="allowtransparency"> #include <iostream.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <stdio.h>

class Strings {
   char *p;
   int size;
public:
   Strings(char *str);
   Strings(void);
   Strings(const Strings &obj);           // Copy constructor
   ~Strings(void) {delete [] p;}

friend ostream &operator<<(ostream &stream, Strings &obj);
friend istream &operator>>(istream &stream, Strings &obj);

   Strings operator=(Strings &obj);       // assign a Strings object
   Strings operator=(char *s);            // assign a quoted string
   Strings operator+(Strings &obj);       // concatenate a Strings object
   Strings operator+(char *s);            // concatenate a quoted string
   friend Strings operator+(char *s, Strings &obj);
            /* concatenates a quoted string with a Strings object */

Strings operator-(Strings &obj); // subtract a Strings object
Strings operator-(char *s); // subtract a quoted string

/* relational operators between Strings objects. Note that the operators could
just as easily return bool, rather than int */

   int operator==(Strings &obj) {return !strcmp(p, obj.p);}
   int operator!=(Strings &obj) {return strcmp(p, obj.p);}
   int operator<(Strings &obj) {return strcmp(p, obj.p) < 0;}
   int operator>(Strings &obj) {return strcmp(p, obj.p) > 0;}
   int operator<=(Strings &obj) {return strcmp(p, obj.p) <= 0;}
   int operator>=(Strings &obj) {return strcmp(p, obj.p) >= 0;}

/* relational operators between Strings object and a quoted character string.
Note that the operators could just as easily return bool, rather than int */

   int operator==(char *s) {return !strcmp(p, s);}
   int operator!=(char *s) {return strcmp(p, s);}
   int operator<(char *s) {return strcmp(p, s) < 0;}
   int operator>(char *s) {return strcmp(p, s) > 0;}
   int operator<=(char *s) {return strcmp(p, s) <= 0;}
   int operator>=(char *s) {return strcmp(p, s) >= 0;}

int strsize(void) {return strlen(p);} // return string size
void makestr(char *s) {strcpy(s, p);} // make quoted string from Strings object

operator char *(void) {return p;} // conversion to char
};

Strings::Strings(void)
{
   size = 1;
   p = new char[size];
   if(!p)
    {
      cout << "Allocation error!" << endl;
      exit(1);
    }
   *p = '/0';
}

Strings::Strings(char *str)
{
   size = strlen(str) + 1;
   p = new char[size];
   if(!p)
    {
      cout << "Allocation error!" << endl;
      exit(1);
    }
   strcpy(p, str);
}

Strings::Strings(const Strings &obj)
{
   size = obj.size;
   p = new char[size];
   if(!p)
    {
      cout << "Allocation error!" << endl;
      exit(1);
    }
   strcpy(p, obj.p);
}

ostream &operator<<(ostream &stream, Strings &obj)
{
stream << obj.p;
return stream;
}

istream &operator>>(istream &stream, Strings &obj)
{
char t[255]; // arbitrary string length--yours can be larger
int len;

   for(len=0; len<255; len++)
    {
      stream.get(t[len]);
      if(t[len]=='/n')
         break;
      if(t[len]=='/b')
         if(len)
          {
            len--;
            cout << "'/b'";
          }
    }
   t[len]='/0';
   len++;

   if(len>obj.size)
    {
      delete obj.p;
      obj.p = new char[len];
      if(!obj.p)
       {
         cout << "Allocation error!" << endl;
         exit(1);
       }
      obj.size = len;
    }
   strcpy(obj.p, t);
   return stream;
}

Strings Strings::operator=(Strings &obj)
{
Strings temp(obj.p);

   if(obj.size > size)
    {
      delete p;
      p = new char[obj.size];
      size = obj.size;
      if(!p)
       {
         cout << "Allocation error!" << endl;
         exit(1);
       }
    }
   strcpy(p, obj.p);
   strcpy(temp.p, obj.p);
   return temp;
}

Strings Strings::operator=(char *s)
{
int len = strlen(s) + 1;

   if(size < len)
    {
      delete p;
      p = new char[len];
      size = len;
      if(!p)
       {
         cout << "Allocation error!" << endl;
         exit(1);
       }
    }
   strcpy(p, s);
   return *this;
}

Strings Strings::operator+(Strings &obj)
{
int len;
Strings temp;

   delete temp.p;
   len = strlen(obj.p) + strlen(p) + 1;
   temp.p = new char[len];
   temp.size = len;
   if(!temp.p)
    {
      cout << "Allocation error!" << endl;
      exit(1);
    }
   strcpy(temp.p, p);
   strcat(temp.p, obj.p);
   return temp;
}

Strings Strings::operator+(char *s)
{
int len;
Strings temp;

   delete temp.p;
   len = strlen(s) + strlen(p) + 1;
   temp.p = new char[len];
   temp.size = len;
   if(!temp.p)
    {
      cout << "Allocation error!" << endl;
      exit(1);
    }
   strcpy(temp.p, p);
   strcat(temp.p, s);
   return temp;
}

Strings operator+(char *s, Strings &obj)
{
int len;
Strings temp;

   delete temp.p;
   len = strlen(s) + strlen(obj.p) + 1;
   temp.p = new char[len];
   temp.size = len;
   if(!temp.p)
    {
      cout << "Allocation error!" << endl;
      exit(1);
    }
   strcpy(temp.p, s);
   strcat(temp.p, obj.p);
   return temp;
}

Strings Strings::operator-(Strings &substr)
{
   Strings temp(p);
   char *s1;
   int i,j;

   s1 = p;
   for(i=0; *s1; i++)
    {
      if(*s1!=*substr.p)
       {
         temp.p[i] = *s1;
         s1++;
       }
      else
       {
         for(j=0; substr.p[j]==s1[j] && substr.p[j]; j++)
            ;
         if(!substr.p[j])
          {
            s1 += j;
            i--;
          }
         else
          {
            temp.p[i] = *s1;
            s1++;
          }
       }
    }
    temp.p[i] = '/0';
    return temp;
}

Strings Strings::operator-(char *substr)
{
   Strings temp(p);
   char *s1;
   int i,j;

   s1 = p;
   for(i=0; *s1; i++)
    {
      if(*s1!=*substr)
       {
         temp.p[i] = *s1;
         s1++;
       }
      else
       {
         for(j=0; substr[j]==s1[j] && substr[j]; j++)
            ;
         if(!substr[j])
          {
            s1 += j;
            i--;
          }
         else
          {
            temp.p[i] = *s1;
            s1++;
          }
       }
    }
    temp.p[i] = '/0';
    return temp;
}

void main(void)
{
   Strings s1("A sample program which uses string objects./n");
   Strings s2(s1);
   Strings s3;
   char s[80];

   cout << s1 << s2;
   s3 = s1;
   cout << s3;
   s3.makestr(s);
   cout << "Converted to a string: " << s;

s2 = "This is a new string.";
cout << s2 << endl;

   Strings s4("This is a new string, too.");
   s1 = s2 + s4;
   cout << s1 << endl;

   if(s2==s3)
      cout << "Strings are equal." << endl;
   if(s2!=s3)
      cout << "Strings are not equal." << endl;
   if(s1<s4)
      cout << "s1 is less than s4." << endl;
   if(s1>s4)
      cout << "s1 is greater than s4." << endl;
   if(s1<=s4)
      cout << "s1 is less than or equal to s4." << endl;
   if(s1>s4)
      cout << "s1 is greater than or equal to s4." << endl;

if(s2 > "ABC")
cout << "s2 is greater than 'ABC'" << endl << endl;

   s1 = "one two three one two three/n";
   s2 = "two";
   cout << "Initial string: " << s1;
   cout << "String after subtracting two: ";
   s3 = s1 - s2;
   cout << s3;

   cout << endl;
   s4 = "Jamsa's C/C++ ";
   s3 = s4 + "Programmer's Bible/n";
   cout << s3;
   s3 = s3 - "C/C++";
   s3 = "This is " + s3;
   cout << s3;

   cout << "Enter a string: ";
   cin >> s1;
   cout << s1 << endl;
   cout << "s1 is " << s1.strsize() << " characters long." << endl;
   puts(s1);

   s1 = s2 = s3;
   cout << s1 << s2 << s3;
   s1 = s2 = s3 = "Program finished./n";
   cout << s1 << s2 << s3;
}