my code is messed up says the compiler

[0927]

here it is

#include <iostream.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <windows.h>
#include <dos.h>
#include <string.h>

#define PROG_NAME "se"

//variables
char message[1000];
//functions
void encypt ();
void decrypt ();
char EncryptChar ();
void EncryptString ();
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::code starts here

char EncryptChar(char ch)
{
    if (ch == 'Z')
    {
      return 'A';
    }
    if (ch == 'z')
    {
      return 'a';
    }
    return ch + 1;
}

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

void encrypt()
{
cout<<"Enter Message to Encrypt:"<<endl;
cin.getline(message, 1000, '\n');
EncryptString(message);
}

void decrypt()
{
cout<<"Error"<<endl;
}

int main(int argc, char* argv[])
{
//Command line arguements =)
if(argc != 3)
  {
    cout<<"Error, Bad Input."; 
    return 0;   
  }

if(argv[2] == '-')
{

if((argv[3] == 'e') || (argv[3] == 'E'))
{
system("cls");
encrypt();
}
else if((argv[3] == 'd') || (argv[3] == 'D'))
{
system("cls");
decrypt();
}
else
{
cout<<"Error Bad Input, Read the ReadMe File"<<endl;
return 0;
}

}
else
{
cout<<"Error Bad Input, Read the ReadMe File"<<endl;
return 0;
}


return 0;
}

im useing bcc 5.5 it says:
69: Cannot convert 'char' to char *' in function main(int, char * *)
72:same thing as above
72:Same thing
77:same thing
77:same thing

[Prelude]

I got 18 errors total.

>// ::::::::::::::::::::::::::::::::::::::::::::::::::
::::::::code starts here

This is two lines, a C++ comment only works for one line but that may have been caused by the board formatting.

>if(argv[2] == '-')
This and other lines similar to this are your problems. argv is an array of pointers to strings, when you try to test a const string and a char for equality the compiler chokes. Also, anything not separated by whitespace will be considered a single string in argv so assuming your command line input is

c:\>test.exe -e

The program will take test.exe as argv[0] and -e as argv[1]. So you could copy argv[1] into an array and then parse it, or use strcmp( argv[1], "-e" ); to test for equality.

-Prelude

[0927]

i fixed my earlier problems now it is this

#include <iostream.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <windows.h>
#include <dos.h>
#include <string.h>

#define PROG_NAME "se"

//variables
char message[1000];
//functions
char EncryptChar (char ch);
void EncryptString (char *str);
void encypt ();
void decrypt ();


char EncryptChar(char ch)
{
    if (ch == 'Z')
    {
      return 'A';
    }
    if (ch == 'z')
    {
      return 'a';
    }
    return ch + 1;
}

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

void encrypt()
{
cout<<"Enter Message to Encrypt:"<<endl;
cin.getline(message, 1000, '\n'); 
EncryptString(message);
}

void decrypt()
{
cout<<"Error"<<endl;
}

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

if(argc == 2)
{

if(!strcmp(argv[1], "-e"))
{
encrypt();
}
else
{
cout<<"Error, Bad Input 2, se -e,-d"<<endl;
return 0;
}

}
else
{
cout<<"Error, Bad Input, se -e or -d";
return 0;
}

return 0;
}

it compiles and runs but when i call
se -e
it asks for the string to encypt i enter it then a message box pops up and says it has preformed and illegal action

[tim545666]

I don't see your error but
char EncryptChar(char ch)
{
if (ch == 'Z')
{
return 'A';
}
if (ch == 'z')
{
return 'a';
}
return ch + 1;
}

would be better as

char EncryptChar(char ch)
{
if (ch == 'Z')
{
return 'A';
}
else if (ch == 'z')
{
return 'a';
}
else return ch + 1;
}

[Prelude]

Please excuse my laziness, your code worked for me when I broke it down...so I just rewrote it. :P

#include <iostream>
using namespace std;

void cryptString(char *str, const char crypt);
char cryptChar(char ch, const char crypt);

/* argv should have three parameters: The file name,
** the line argument to determine encrypt or decrypt,
** and the line argument to do the opposite of the 
** previous argument, just to make sure it worked.
**
** Line arguments are tested as e and d, but change
** the test and you can change the argument.
*/
int main(int argc, char *argv[])
{   char message[1000] = {0};
	
    if( argc != 3 )
        // Never do this, always let the user know
        return EXIT_FAILURE;

    cout << "Enter a message to crypt: " << flush;
    cin.getline( message, 1000, '\n' );

    // Before
    cout << message << endl;
    cryptString(message, *argv[1]);
    // After
    cout << message << endl;
    cryptString(message, *argv[2]);
    // Back to original
    cout << message << endl;

    getchar();

    return EXIT_SUCCESS;
}

void cryptString(char *str, const char crypt)
{
    while (*str != '\0') {
        *str = cryptChar(*str, crypt);
        str++;
    }
}

char cryptChar(char ch, const char crypt)
{
    /* I used a simple rotate 13 encryption
    ** but you can use whatever you want
    */
    if( crypt == 'e' )
        ch += 13;
    else if( crypt == 'd' )
        ch -= 13;
    return ch;
}

Your error sounds like it may be implementation defined.

-Prelude

[*ClownPimp*]

> I don't see your error but ...
>would be better as

I wrote that funciton! How dare you critque my work!
Since the function extis at the return statement if the condition is true, it doesnt make a difference

also, your suggestion always flags a warning on my compiler saying not all possible execution lines return a value, and my god I hate warnings.

[*ClownPimp*]

the error in your code is here:

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

since '=' is evaluated right to left, *str++ advances the pointer before the target value is set in the correct spot, so the NULL byte is overwritten. But on some compilers, a char array is initialized to zero automatically, so that would explain why the code may seem to work on some compilers and not others.

Here is the fix:

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

notice the incrementation happens after the equation has been evaluated

[iain]

int argc, char* argv[])

this isnt really necessary - you can just call int main (void)

[0927]

im redoing it to invovle a key and useing files instead of input ought to be pretty nice thanks for the help fixing those problems.oh ya and about file i/o if i just use
ifstream(file.txt)
does it look in the directory the programs in?

[*ClownPimp*]

yep

[zMan]

this line is confusing...

if(!strcmp(argv[1], "-e"))
{
encrypt();
}


strcmp can return 0 less than 0(usually -1) or greater than 0 (usually 1) !0 !-1 !1??????

why not...

if(strcmp(argv[1], "-e") != 0 )
{
encrypt();
}

instead...

[Unregistered]

You're correct,

if(!strcmp(argv[1], "-e"))

is potentially confusing but the more explicit form would be:

if(strcmp(argv[1], "-e") == 0)

and not

if(strcmp(argv[1], "-e") != 0)


What the original code is trying to say, I believe, is if the second command line argument is the flag -e then you should do the encryption. Since argv[1], if it exists, and -e are strings you would routinely use strcmp() to compare them. If they are the same string then strcmp() will return 0. However, 0 is interpreted as false and any non-zero value is interpreted as true, so the original line will resolve to if(!0) which means if(true). I like the more explicit form personally, but to save keystrokes, the form as presented is commonly used, so it pays to get used to it.