Encrypter- I need help

#include <iostream>
using namespace std;

int main()
{
    char key;
    char str[9000];
    cout << "Enter the message you want to encrypt: "<<endl;
    cin >> str;
    cout << "Enter your encryption key(any character): ";
    cin >> key;
     for(int i = 0;str[i]; i++)
     {
             str[i] = str[i] ^ key;
     }
    cout << "\nHere is your encrypted message: \n" << str << endl << "\n use key of: " << key << " to decode.\n";
    system("pause");
    return 0;
}

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

void encrypt();
void decrypt();
void start();

int main()
{
    start();
    
    system("pause");
    return 0;
}

void start(){
    char choice;
    cout << "Would you like to encrypt, or Decrypt a file?\n" << endl;
    cout << "q.) Quit\n";
    cout << "e.) Encrypt/Decrypt\n";
    
    cin >> choice;


    switch(choice){
    case 'q':
        break;

    case 'e':
        system("cls");
        decrypt();
        system("cls");
        start();
        break;

    default:
        system("cls");
        start();
        break;
    }
}



void decrypt(){
    ifstream ifile ("encrypt.txt", ios::app);
    char key;
    string iput;


    cout << "Place the text you want to decrypt or encrypt in the file 'encrypt.txt'"<<endl;

    if (ifile.is_open())             // I tested this part and nothing executes within this if statement. idk why?
    {                                // Is it that encrypt.txt isn't open? Why not jst read the file without checking if its open or not?
        while (!ifile.eof())
        {
            getline(ifile, iput);
        }
        ifile.close();
    }

            cout << "What key is the input encrypted in?" << endl;

            cin >> key;    

            for(int i = 0;iput[i]; i++)
            {
             iput[i] = iput[i] ^ key;
            }

            cout << iput << endl;
        
    //ifile << "\nHere is your encrypted message: \n" << iput << endl << "\n use key of: " << key << " to decode.\n";
    //for above to work, class needs to be ofstream, or f stream


    system("pause");
}

void CopyToClipboard(char* text)
{
	HGLOBAL      clipbuffer;    
	char*         temp_ptr ;

	clipbuffer = GlobalAlloc(GMEM_MOVEABLE | GMEM_SHARE, (strlen(text)+1) * sizeof(char));
	temp_ptr = (char*)GlobalLock(clipbuffer);
	strcpy(temp_ptr, text);
	GlobalUnlock(clipbuffer);

	OpenClipboard(0);         // 0 means no window
	EmptyClipboard();
    Se***ipboardData(CF_TEXT, clipbuffer);
	CloseClipboard();
}

// Encrypt.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <windows.h>
using namespace std;

void XOR(BYTE* buffer,long length, char* key)
{
	int keyLength = strlen(key);
	int keyIndex = 0;
	for(int i = 0 ; i< length; i++)
	{
		buffer[i] ^= (BYTE)key[keyIndex++];
		if(keyIndex >= keyLength)
			keyIndex = 0;
	}
}

void CopyToClipboard(char* text)
{
	HGLOBAL      clipbuffer;    
	char*         temp_ptr ;

	clipbuffer = GlobalAlloc(GMEM_MOVEABLE | GMEM_SHARE, (strlen(text)+1) * sizeof(char));
	temp_ptr = (char*)GlobalLock(clipbuffer);
	strcpy(temp_ptr, text);
	GlobalUnlock(clipbuffer);

	OpenClipboard(0);         // 0 means no window
	EmptyClipboard();
    Se***ipboardData(CF_TEXT, clipbuffer);
	CloseClipboard();
}

/// Making the main a void since we don't care about what it returns
void main(int argc, char* argv[])
{
	int bufferSize = 0;
	////define some variables we'll be using
	char* filename = NULL;
	char* outputFile = NULL;
	char* text = NULL;
	char* key = NULL;

	//Parse arguments - could be done better
	for(int i = 0; i < argc; i++)
	{
	 if(_stricmp(argv[i],"/fin")==0 || _stricmp(argv[i],"-fin") == 0)
		 filename = argv[++i];
	 else if(_stricmp(argv[i],"/fout")==0 || _stricmp(argv[i],"-fout") == 0)
		 outputFile = argv[++i];
	 else if(_stricmp(argv[i],"/t")==0 || _stricmp(argv[i],"-t") == 0)
		 text= argv[++i];
	 else if(_stricmp(argv[i],"/k")==0 || _stricmp(argv[i],"-k")==0)
		 key = argv[++i];
	}

	//If we're not being called correctly, print out what we expect
	if((argc != 5 && argc != 7) ||  !key || (!filename && !key) || (filename && !outputFile) || (outputFile && !filename))
	{
		cout << "Encrypt Sample for Why06 by B1ackAnge1" << endl;
		cout << "--------------------------------------" << endl;
		cout << "Usage:" << endl;
		cout << "Encrypt a file using a given key:" << endl;
		cout << "Encrypt.exe /fin file.txt /fout file.out /k key" << endl << endl;
		cout << "Encrypt a string using a given key and place on clipboard" << endl;
		cout << "Encrypt.exe /t sometext /k key" << endl;
		cin.get();
		return;
	}

	if(filename) // same as: if(filename != null)
	{
		bufferSize = strlen(key) * 8192; //Don't ask ;)
		BYTE* buffer = new BYTE[bufferSize];
		FILE *fp = fopen(filename,"r+b");
		FILE *fpout = fopen(outputFile,"w+b");

		while(fp && feof(fp) == 0)
		{
			BYTE* buffer = new BYTE[bufferSize];
			int numBytes = fread(buffer,sizeof(byte),bufferSize,fp);
			XOR(buffer,numBytes,key);
			//long curPos = ftell(fp);
			fwrite(buffer,sizeof(byte),numBytes,fpout);
			fflush(fpout);

			delete[] buffer;
		}
		if(fp) 
			fclose(fp);
		if(fpout)
			fclose(fpout);
	}
	else if(text)
	{
		XOR((byte*)text,strlen(text),key);
		CopyToClipboard(text);
	}
}