Thread: createing my constructer

ok the class is file in a header file and im makeing the constructor I am trying to make a bunch of strings to equal 0 heres what I have tried:

file::file()
{
file_one = "0";
}

trying to compile is says:
Lvalue required in function file::file()

so then I tried:
file::file()
{
file_one = '0';
}

and it said the same thing I am new to this what is going on?

and it still said the same thing it can be \0 or just a 0 or anything like that

what is file_one... (as golfinguy4 stated)

show the rest of you code.

I don't think your problem is there... did you terminate your class with a semicolon? Is your class implementation and declaration in the same file?

show code... use [ code ] [ /code ] tags...

Heres file.h

Code:

#ifndef file_var
#define file_var

class file
{
public:
file();
~file();
void encrypt ();
void decrypt ();
char EncryptChar (char ch);
void EncryptString (char *str);

protected:
char file_one[256];
char file_two[256];  
char contents[1000];
char key[5];
};

#endif

heres main_01.cpp

Code:

#include <iostream.h>
#include <fstream.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <windows.h>
#include "file.h"

file::file()
{
file_one="\0";
file_two="\0";
contents="\0";
key="\0";
}

char file::EncryptChar(char ch)
{
    key[0] = key[1] + key[3];
    key[4] = key[0] * key[2];
    ch = key[4];
    return ch;
}

void file::EncryptString(char *str)
{
    while (*str != '\0')   *str = EncryptChar(*str++);
}

void file::encrypt()
{
cout<<"Enter Files Name"<<endl;
cout<<":";
cin.getline(file_one, 256, '\n');
cout<<"Enter File to Save it to"<<endl;
cout<<":";
cin.getline(file_two , 256, '\n');
cout<<"Enter 5 Digit Key"<<endl;
cout<<":";
cin.getline(key, 5, '\n');

/* Open File */
ifstream ein;
ein.open(file_one);

while(ein.eof() != 1)
{
int x = 0;
x++;
ein>>contents[x];
}

/* Encrypt */
EncryptString(contents);

/* Save */
ofstream eout;
eout.open(file_two);

for(int x = 0; x != 1000; x++)
{
eout<<contents[x];
}

eout.close();

/* Finished */
cout<<"Encryption completed..."<<endl;
cout<<file_one<<" was encypted to "<<file_two<<endl;
cout<<"The key is "<<key<<endl;

Sleep(2500);

exit(0);

}

and when I try to compile it on borland 5.5 this happens:

! Error E2277 .\main_01.cpp 11: Lvalue required in function file::file()
! Error E2277 .\main_01.cpp 12: Lvalue required in function file::file()
! Error E2277 .\main_01.cpp 13: Lvalue required in function file::file()
! Error E2277 .\main_01.cpp 14: Lvalue required in function file::file()

ahhh.. got it...


They are arrays.

You need the [] and a reference array point

Code:

int i;

for (i=0; i < 256;++i)
file_one[i]='\0';

no that didnt work what is the Lvalue it still says that

>file_one="\0";
memset ( file_one, 0, 256 );

And include either string.h or cstring when you work with C strings.

-Prelude

doesnt work I have tried what you said I included both of them did the memset thing didnt work I did the for loop thing with and without the memset thing didnt work what is the Lvalue thing if I knew what it was talking about...

It compiles fine for me when I use memset, here's the constructor code that worked:

Code:

file :: file()
{
  memset(file_one,'\0',256);
  memset(file_two,'\0',256);
  memset(contents,'\0',1000);
  memset(key,'\0',5);
}

An Lvalue is a variable or chunk of memory that allows assignment to itself. So you can assign to an integer i, but not to an expression (i + 3). You can't assign a string to an array of char directly except during initialization:
char string[] = "This is a string"; // This works
string = "This is another string"; // Bzzzt! Illegal

-Prelude

oh I was doing it wrong thanks so much man!