C++ encrypt and decrypt secret messages using files - c++

Question

I have my prototypes in a header file, but I need some help. I am having some trouble getting the program to compile all the way through. It appears to be getting caught in a loop with the input. Possibly some issues with the functions. Thanks in advance for any input.
#include <iostream>
#include <conio.h>
#include "header.h"
#include <fstream>
class Caesar
{
public: void readText(char *input);
void encrypt(char *input,char *output,char *key);
void decrypt(char *input,char *output,char *key);
};
void main()
{
Caesar a;
char key[1000];
ifstream fin;
int choice;
char input[100],output[100];
cout<<"\n Enter input file: ";
cin>>input;
cout << input;
cout<<"\n Enter output file: ";
cin>>output;
cout <<output;
cout<<"\n Enter key: ";
cin>>key;
cout <<key;
cout<<"\n\n 1. Encrypt\n 2. Decrypt\n\n Select choice(1 or 2): "<< endl;
cin >> choice;
cout << choice;
a.readText(input);
if(choice==1)
{
a.encrypt(input,output,key);
}
if(choice==2)
{
a.decrypt(input,output,key);
}
else
{
cout<<"\n\n Unknown choice";
}
}
void Caesar::readText(char *input)
{
ifstream reader;
char buf;
reader.open(input);
cout<<"\n\n <--- "<<input<<" --->\n";
buf=reader.get();
while(!reader.eof())
{
cout<<buf;
buf=reader.get();
}
reader.close();
}
void Caesar::encrypt(char *input,char *output,char *key)
{
ifstream reader;
ofstream writer;
char buf;
reader.open(input);
writer.open(output);
buf=reader.get();
while(!reader.eof())
{
if(buf>='a'&&buf<='z')
{
buf-='a';
buf+=key[buf];
buf%=26;
buf+='A';
}
writer.put(buf);
buf=reader.get();
}
reader.close();
writer.close();
readText(input);
readText(output);
}
void Caesar::decrypt(char *input,char *output,char *key)
{
ifstream reader;
ofstream writer;
char buf;
reader.open(input);
writer.open(output);
buf=reader.get();
while(!reader.eof())
{
if(buf>='A'&&buf<='Z')
{
buf-='A';
buf+=26-key[buf];
buf%=26;
buf+='a';
}
writer.put(buf);
buf=reader.get();
}
reader.close();
writer.close();
readText(input);
readText(output);
}

Answer 1

if(choice=1)
should be
if(choice==1)
and also in the other if
In your case, you are assigning the value 1 to choice, then test if choice is true, and it is, since any non-zero numeral type is implicitly casted to bool true.

Answer 2

I have just executed your code and tried debugging it and took a screen shot
you program gets into a loop after entering the choice.there is no problem with cin>>.

Answer 3

From your comments, it seems like you're just trying to debug main. Everything seems to work fine. What are you inputting for key? If it's a very large integer, that may be your problem as it might exceed the maximum integer range and cause overflow.
Your key is an integer variable. You are inputting a string for the file name that holds your key, so that should be changed to a C string array. Change all of the passed key parameters to char* instead of int.
You have an infinite loop when the readText() function is called.
Maybe try this:
void Caesar::readText(char *input)
{
ifstream reader(input);
if(reader.is_open())
{
char buf;
cout<<"\n\n <--- "<<input<<" --->\n";
while(reader.get(buf))
{
cout << buf;
}
}
reader.close();
}
Make sure that your text file is in the same folder as your code. See this for more details: ifstream not opening file