Re: [Dev-C++] newbie questions without answer

[Carlos d. M. <cg...@wo...>]

The code post is only a part, talking about the files he gave (perhaps
you didn't receive the files?).
I wrote principally for him, but as you want see all, here is the code:

The code for the struct thing (newbiequestion.cpp) is:
#include <iostream>
#include <stdlib.h>
#include <string.h>

struct date{
   int month;
   int day;
   int year;
};

struct employ{
  char *first;
  char *second;
  date eyear;  /*i want to use a reference to the year in the first
struct
               but then i get an error message from the compiler since i
didn't
               initialize eyear!! how am i to get rid of this
problem??*/
};
int main()
{
      date d;
      employ e;
      d.day=3D30;
      d.month=3D8;
      d.year=3D1982;
      e.eyear =3D d;
      e.first=3Dnew char [strlen("senem")];   // a way of doing this
shortly??
      e.second=3Dnew char [strlen("beken")];
      e.first=3D"senem";
      e.second=3D"beken";

      cout<<e.first<<" "<<e.second<<endl;
      cout<<"birthday:\n"
      <<e.eyear.day<<"/"<<e.eyear.month<<"/"<<e.eyear.year<<endl;
      system("PAUSE");
      return 0;
}

Another is the stringclas.cpp file which source is:

#include <iostream>
#include <stdlib.h>
#include <cassert>
#include <string.h>
#include <iomanip.h>

class string{
 friend ostream &operator<<(ostream &,const string&);
 friend istream &operator>>(istream &,string&);
public:
 string(const char * =3D"");

 string(const string &);
 ~string();
 const string &operator=3D(const string &);
 const string &operator+=3D(const string &);
 bool operator!()const;
 bool operator=3D=3D(const string&)const;
 bool operator<(const string&)const;
 bool operator!=3D(const string& right)const
 {return !(*this=3D=3Dright);}
 bool operator>(const string& right)const
    {return (right<*this);}
 bool operator<=3D(const string& right)const
    {return !(right<*this);}
 bool operator>=3D(const string& right)const
    {return !(*this<right);}
 char &operator[](int);
 const char &operator[](int)const;
 string operator()(int,int);
 int getlength()const;
private:
 int length;
 char * sptr;
 void setstring(const char*);
};

string::string(const char *s):length(strlen(s)){
  cout<<"conversion constructor :"<<s<<"\n";
  setstring(s);
}

string::string(const string&copy):length(copy.length){
  cout<<"copy constructor: "<<copy.sptr<<"\n";
  setstring(copy.sptr);
}

string::~string(){
  cout<<"destructor: "<<sptr<<"\n";
  delete[]sptr;
}

const string &string::operator=3D(const string &right){  //burda nie ref
var??
  cout<<"operator=3D called\n";

  if(&right!=3Dthis){
   delete[]sptr;
   length=3Dright.length;
   setstring(right.sptr);
  }
  else
   cout<<"attempted assignment of a string to itself\n";

   return *this;
}

const string &string::operator+=3D(const string &right){

char *string1=3Dnew char[length+right.length+1];    ///DON'T MODIFY THE
SIZE
strcpy(string1,sptr);    /* i tried to change this part a little
                         so that the first string is not modified,but
then
                         the program started to terminate abnormally
                         and i have absolute no idea what i did  wrong!!

                         here is the original:

                          char *tempptr=3Dsptr;
                          lenght+=3Dright.length;
                          sptr=3Dnew char [length+1];
                          assert(sptr!=3D0);
                          strcpy(sptr,tempptr);
                          strcat(sptr,right.ptr);
                          delete[]tempptr;
                          return *this;*/
strcat(string1,right.sptr);


}

bool string::operator!()const{return length=3D=3D0;}

bool string::operator=3D=3D(const string &right)const
  {return strcmp(sptr,right.sptr)=3D=3D0;}

bool string::operator<(const string &right)const
  {return strcmp(sptr,right.sptr)<0;}

char &string::operator[](int subscript){
  assert(subscript>=3D0&&subscript<length);
  return sptr[subscript];
}

const char &string::operator[](int subscript)const{
 assert (subscript>=3D0&&subscript<length);
 return sptr[subscript];
}

string string::operator()(int index,int sublength){
   assert(index>=3D0&&index<length&&sublength>=3D0);

   int len;

   if((sublength=3D=3D0)||(index+sublength))
      len=3Dlength-index;
   else
      len=3Dsublength;

      char *tempptr=3Dnew char[len+1];
      assert(tempptr!=3D0);
      strncpy(tempptr,&sptr[index],len);
      tempptr[len]=3D'\0';

      string tempstring(tempptr);
      delete[]tempptr;

      return tempstring;
}

int string::getlength()const{return length;}

void string::setstring(const char *string2){
   sptr=3Dnew char[length+1];
   assert(sptr!=3D0);
   strcpy(sptr,string2);
}

ostream &operator<<(ostream &output,const string &s){
  output<<s.sptr;
  return output;
}

istream &operator>>(istream &input,string &s){
  char temp[100];

  input>>setw(100)>>temp;
  s=3Dtemp;
  return input;
}


int main()
{
      string s1("happy"),s2("birthday"),s3;

      cout<<"s1 is\""<<s1<<"\";s2 is\""<<s2
          <<"\";s3 is\""<<s3<<'\"'
          <<"\n the results of comparing s2 and s1:"
          <<"\ns2=3D=3Ds1 yields"
          <<(s2=3D=3Ds1?"true":"false")
          <<"\ns2!=3Ds1 yields "
          <<(s2!=3Ds1 ?"true":"false")
          <<"\ns2>s1 yields "
          <<(s2>s1?"true":"false")
          <<"\ns2<s1 yields "
          <<(s2<s1 ?"true":"false")
          <<"\ns2>=3Ds1 yields "
          <<(s2>=3Ds1 ?"true":"false")
          <<"\ns2<=3Ds1 yields "
          <<(s2<=3Ds1?"true":"false");

          cout<<"\n\n testing !s3:\n";
          if(!s3){
             cout<<"s3 is empty,assigning s1 to s3;\n";
             s3=3Ds1;
             cout<<"s3 is\""<<s3<<"\"";
          }

          cout<<"\n\n s1+=3Ds2 yields s1=3D";
          s1+=3Ds2;
          cout<<s1;

          cout<<"\n\n s1+=3D\"to you\"yields\n";
          s1+=3D"to you";
          cout<<"s1 =3D "<<s1<<"\n\n";

          cout<<"the substring od s1 starting at\n"
              <<"location 0 for 14 characters,s1(0,14),is:\n"
              <<s1(0,14)<<"\n\n";

          cout<<"the substring of s1 starting at \n"
             <<"loaction 15,s1(15,0),is:" //<- 15 , which is out of
bounds due to the +=3D modification
             <<s1(15,0)<<"\n\n";

          string *s4ptr=3Dnew string(s1);
          cout<<"s4ptr =3D"<<*s4ptr<<"\n\n";

          cout<<"assigning *s4ptr to *s4ptr\n";
          *s4ptr=3D*s4ptr;
          cout<<"*s4ptr=3D "<<*s4ptr<<"\n";

          delete s4ptr;

          s1[0]=3D'H';
          s1[6]=3D'B';
          cout<<"\n s1 after s1[0]=3D'H' and s1[6]=3D'B' is: "
              <<s1<<"\n\n";


      system("PAUSE");
      return 0;
}
Ioannis Vranos escribi=F3:

>  -----Original Message-----
> From: dev...@li...
> [mailto:dev...@li...] On Behalf Of Carlos
> Garc=EDa del Monte
> Sent: Sunday, August 11, 2002 3:49 PM
> To: dev-cpp-users-list
> Subject: Re: [Dev-C++] newbie questions without answer
>
>
>
>      newbiequestion.cpp
>
>      struct employ{
>        char *first;
>        char *second;
>        date eyear;  /*i want to use a reference to the year in
>      the first struct
>
> I do not see any reference here. Also what first struct?
>
>
>                     but then i get an error message from the
>      compiler since i didn't
>                     initialize eyear!! how am i to get rid of
>      this problem??*/
>
> Provide a default constructor or default arguments to the provided
> constructor.
>
>
>      I have no problems compiling it.
>      employvar.eyear.(day/month/year)=3D x;
>
> That's a bit strange.
>
>      Or
>      date *eyear
>      employvar.eyear->day=3Dx.
>
>      Or
>      date *eyear; in employer struct.
>      datevar.day =3D x;
>      employvar.eyear =3D datevar;
>      Or datevar.day=3Dx;
>      datevar.eyear =3D &datevar;
>
> I hope you know what you are doing in the above.
>
>      The other question about shorter way. I don't understand.
>
>      In the stringclass what happens is that when you modify the
>      +=3D operator, so the string of the left hand string object is
>      no midified you make that neither it size is modified
>      (evidently), but then, ine the code, at line 178 - 190, the
>      code assumes that function has not been changed (you did not
>      adapted it to your modifications), so as it wants to output
>      the substrings from a subscript to another position, and the
>      positions are not found through object's functions, they are
>      put ad hoc, the code at this lines are intended so you had
>      just added s2 to s1, so s1 is "happy birthday to you", which
>      has 21 characters, and there the code is "substring from 0,
>      14 and after from 15, 0", which are ranges that would be in
>      s1, but you modified it in a way such now s1 is "happy",
>      five chars, so when you ask for range 15,0  you're giving a
>      range which is out of the bounds of s1.
>
>      The burda nie ref var, that's the way....
>
> I am not good at understanding technical problems from text. Please
> provide some example code with comments.
> Ioannis
>
> * Ioannis Vranos
> * Programming pages: http://www.noicys.cjb.net* Alternative URL:
> http://run.to/noicys
>