Text Encoder/ Decoder in C++

Yo, I currently have a project for my (Basic) Computer programming class which consists of making a simple Text Encoder/Decoder.

It'll read text from a file (named as "input.txt"), transformed/encoded using an encoding algorithm (to be created by me.) and saved into another file (named as "output.txt"). The decoder is simply this process in reverse only with the file named as "decoded.txt".

The problem I'm facing is I have no idea how an encoding algorithm (as well as the script that allows the encoder/decoder to read from the file) works or is made. This past term was literally my first experience with C++.

So far, here's what I've managed to come up with: (Note: I'm using Bloodshed Dev-C++)

Code:

#include <math.h> #include <stdio.h> #include <conio.h> #include <stdlib.h> // The libraries int main(){ int option; // Variable for selection. printf("Select a Number to select a Function\n"); // The choices and selection. printf("1. Encode\n"); printf("2. Decode\n"); printf("3. Close\n\n"); scanf("%i",&option); switch(option){case 1: printf("\nYOU SHALL ENCODE!"); // Placeholder for Encoding script break; case 2: printf("\nYOU SHALL DECODE!"); // Placeholder for Decoding script break; case 3: printf("\nPress any key to continue."); // Script for cancellation. break; default: printf("\nINVALID, TRY AGAIN NEXT TIME."); } getch();}

Any form of advice or tutorials (which a complete idiot could understand XD) would be much appreciated.

Regards,

Joe

C++ Programming neophyte

the basic idea is that you apply some sort of transformation to the plain text - xor for example - that when applied to the encoded text, gives the original plain text.

on a side note: dev-C++ is ANCIENT in terms of develpment environments. get code::blocks or eclipse or MSVC++ Express

Lots of ways to encode text.

ROT13 - Wikipedia, the free encyclopedia
Base64 - Wikipedia, the free encyclopedia
XOR cipher - Wikipedia, the free encyclopedia
Data Encryption Standard - Wikipedia, the free encyclopedia
Huffman coding - Wikipedia, the free encyclopedia

Take your pick, there's lots more should you find that none of these fit the spirit of the assignment.

Have a look at XOR cipher - Wikipedia, the free encyclopedia

Very simple algorithm; in order to encrypt, do a xor on each byte of your text and store that result. In order to de-crypt, again do xor's with same value on every byte of the previously encrypted text et voila...

Right, I'll take a look at them later. (I have Finals today, so yeah.)

@Elkvis: I'll keep that in mind when I get LBYEC72, which would be two terms from now. (The next course after this course I'm taking.)

Did you accidentally post this in the wrong section?

No I didn't, I originally had no idea how to go about things but now I have an inkling as to how to do it.

My only problem now is the encryption part of the program. (and the subsequent writing into another file.)

Then how come you posted C in C++?

That was C? I didn't know. :/

Quote:

Originally Posted by Joe_Allen

That was C?

Yep. The most significant difference is in the #includes at the top -- those are C library includes. The C++ library uses slightly different versions of those:

Code:

#include <cmath> #include <cstdio> #include <conio.h> // dunno about this one #include <cstdlib>

These allow you to use the standard C functions you are using in a C++ program (notice the form: stdio.h = cstdio, etc). You should not use a C++ compiler with the other headers; altho in practice they are nearly identical and so work, there could be slight differences which will lead to problems.

All I know about conio.h is that it is from a (non-standard) Borland C library originally for MS-DOS. It may work fine with a C++ compiler, but then again, it may not. Unless you know you need it for something, just leave it out.

Of course, if you are looking to learn C++, you might want to use native C++ stuff from <iostream>, like cout, instead of printf from <cstdio>.

Please don't use Conio.h!

Its a horrible, horrible thing, and it'll leave you with no friends.

> That was C? I didn't know. :/
Isn't it a bit late in the course to discover that you've been learning the wrong language?

If your tutor has just been feeding you stuff on the basis "well it compiles", then you need to get your money back!

Quote:

Originally Posted by Joe_Allen

Yo, I currently have a project for my (Basic) Computer programming class which consists of making a simple Text Encoder/Decoder.

It'll read text from a file (named as "input.txt"), transformed/encoded using an encoding algorithm (to be created by me.) and saved into another file (named as "output.txt"). The decoder is simply this process in reverse only with the file named as "decoded.txt".

The problem I'm facing is I have no idea how an encoding algorithm (as well as the script that allows the encoder/decoder to read from the file) works or is made. This past term was literally my first experience with C++.

So far, here's what I've managed to come up with: (Note: I'm using Bloodshed Dev-C++)

Code:

#include <math.h> #include <stdio.h> #include <conio.h> #include <stdlib.h> // The libraries int main(){ int option; // Variable for selection. printf("Select a Number to select a Function\n"); // The choices and selection. printf("1. Encode\n"); printf("2. Decode\n"); printf("3. Close\n\n"); scanf("%i",&option); switch(option){case 1: printf("\nYOU SHALL ENCODE!"); // Placeholder for Encoding script break; case 2: printf("\nYOU SHALL DECODE!"); // Placeholder for Decoding script break; case 3: printf("\nPress any key to continue."); // Script for cancellation. break; default: printf("\nINVALID, TRY AGAIN NEXT TIME."); } getch();}

Any form of advice or tutorials (which a complete idiot could understand XD) would be much appreciated.

Regards,

Joe

C++ Programming neophyte

It's been said before, but this is "C". The easiest way to tell is that all standard headers require the .h extension (only non-standard in c++) and that you are using print/scanf instead of cin/out.