C++ Encryption Project

This is my final project for my Intro C++ course.
I am having issues with both ciphers. Just looking for a bit of guidance or some changes I need to make in my program to get it fully functional. Thanks in advance!

The project requirements are as follows:
Program Specification:
Using the techniques presented during this semester create a complete C++ program to emulate an Encryption/Decryption Machine. The machine will be capable of the following:
 Encrypt a string entered by the user
 Choose between two different encryption methods
 Decrypt a string entered by the user
 Choose between two different decryptions methods
 Decrypt without knowing the encryption method (provide all possible outputs)

The interface must be professional and fully intuitive to the user

The program will be menu driven.

The program will use a class to define and implement each of the methods as member functions and will store the original string and the encrypted/decrypted strings as data members.

In addition to using a class you must also use all the major structures we used this semester including:
Selection statements (if, if-else, switch) the appropriate one(s) of course
Loops (while, for, do-while) the appropriate one(s) of course
Standard Libraries (don’t recreate the wheel)
Functions
Arrays

The two encryption/decryption methods are:

Substitution cipher
Transposition cipher

You will need to research each and determine how to implement them. Remember in the case of the transposition cipher there are 25 possible shifts, you must be able to choose or test for all 25 options.

================================================================

 #include<iostream>
#include<stdio.h>
#include<string.h>
#include<conio.h>

using namespace std;

class Substitution // Substitution Cipher class
{
	char str[500];

public:
	void sgetstring(void);      // method to get input string and key
	void sencryption(void);     // encryption method for Substitution Cipher
	void sdecryption(void);		// decryption method for Substitution Cipher
};
void Substitution::sgetstring()
{
	int size = 500;
	cout << "\n Enter the Input String: ";      // Input for Substitution Cipher
	cin.getline(str, size, '\n');
}
void Substitution::sencryption()
{
	int key, i, t1;
	char c;
	cout << "\n Enter Key: ";
	cin >> key;
	cout << "\n Encryption : ";
	//Encryption
	for (i = 0; i<strlen(str); i++)
	{
		c = str[i];

		if (c == -1)
			break;
		if (isupper(c))
		{
			t1 = (int)c - (int) 'A';
			t1 = (t1 + key) % 26;
			t1 = t1 + (int) 'A';
			cout << (char)t1;
		}
		else if (islower(c))
		{
			t1 = (int)c - (int) 'a';
			t1 = (t1 + key) % 26;
			t1 = t1 + (int) 'a';
			cout << (char)t1;
		}
		else{
			cout << c;
		}
	}
}
void Substitution::sdecryption()
{
	int key, i, t1;
	char c;
	cout << "\n Decryption : \n";
	//decryption
	for (key = 0; key<26; key++)
	{
		for (i = 0; i<strlen(str); i++)
		{
			c = str[i];

			if (c == -1)
				break;
			if (isupper(c))
			{
				t1 = (int)c - (int) 'A';
				t1 = (t1 - key + 26) % 26;
				t1 = t1 + (int) 'A';
				cout << (char)t1;
			}
			else if (islower(c))
			{
				t1 = (int)c - (int) 'a';
				t1 = (t1 - key + 26) % 26;
				t1 = t1 + (int) 'a';
				cout << (char)t1;
			}
			else{
				cout << c;
			}
		}
		cout << "\n";
	}
	//ending
}

class Transposition            // Transposition Cipher class
{
	char arr[22][22], darr[22][22], message[111], emessage[111], retmessage[111], key[55];
	char temp[55], temp2[55];

public:
	void tgetstring();		      // method to get input string and key        
	void tencryption();           // encryption method for Transposition Cipher
	void tdecryption();           // decryption method for Transposition Cipher
	void tcipher(int i, int c);   // Transposition Cipher module
	int tfindMin();               // method to find the minimum values from the given key
	void tmakeArray(int, int);    // method to get the result encrypted / decrypted array 
};
void Transposition::tgetstring()
{
	cout << "\n Enter the key\n";
	cin.getline(key, 111, '\n');
	//gets(key); 
	cout << "\n Enter message to be ciphered\n";
	cin.getline(message, 111, '\n');
	//gets(message); 	
}
void Transposition::tencryption()
{
	int i, j, klen, emlen, flag = 0;
	int r, c, index, rows, k = 0;

	strcpy_s(temp, key);
	klen = strlen(key);

	k = 0;
	for (i = 0;; i++)
	{
		if (flag == 1)
			break;

		for (j = 0; key[j] != '\0'; j++)
		{
			if (message[k] == '\0')
			{
				flag = 1;
				arr[i][j] = '-';
			}
			else
			{
				arr[i][j] = message[k++];
			}
		}
	}
	r = i;
	c = j;

	for (i = 0; i < r; i++)
	{
		for (j = 0; j < c; j++)
		{
			cout << arr[i][j];
		}
		cout << "\n";
	}
	cout << "\n Encrypted message is\n";
	k = 0;
	for (i = 0; i < klen; i++)
	{
		index = this->tfindMin();
		this->tcipher(index, r);
	}
	emessage[k] = '\0';
	//printf("\nEncrypted message is\n");
	//for (i = 0; i<strlen(emessage); i++)
	//{    		
	//    printf("%c", emessage[i]);
	//}
	cout << "\n\n";
}
void Transposition::tdecryption()
{
	int i, j, klen, emlen, flag = 0;
	int r, c, index, rows, k;
	//deciphering
	emlen = strlen(message);
	klen = strlen(key);
	//emlen is length of encrypted message
	strcpy_s(temp, key);
	rows = emlen / klen;
	//rows is no of row of the array to made from ciphered message
	k = 0;
	for (i = 0;; i++)
	{
		if (flag == 1)
			break;

		for (j = 0; key[j] != '\0'; j++)
		{
			if (message[k] == '\0')
			{
				flag = 1;
				arr[i][j] = '-';
			}
			else
			{
				arr[i][j] = message[k++];
			}
		}
	}
	r = i;
	c = j;

	j = 0;
	for (i = 0, k = 1; i<emlen; i++, k++)
	{
		//printf("\nEmlen=%d",emlen);
		temp2[j++] = message[i];
		if ((k % rows) == 0)
		{
			temp2[j] = '\0';
			index = this->tfindMin();
			this->tmakeArray(index, rows);
			j = 0;
		}
	}
	cout << "\n Array Retrieved is\n";

	k = 0;
	for (i = 0; i < r; i++)
	{
		for (j = 0; j < c; j++)
		{
			cout << darr[i][j];
			//retrieving message
			retmessage[k++] = darr[i][j];

		}
		cout << "\n";
	}
	retmessage[k] = '\0';

	cout << "\n Message retrieved is\n";

	for (i = 0; retmessage[i] != '\0'; i++)
		cout << retmessage[i];
}
void Transposition::tcipher(int i, int r)
{
	int j, k = 0;
	for (j = 0; j < r; j++)
	{
		{
			emessage[k++] = arr[j][i];
			cout << emessage[k - 1];
		}
	}
	// emessage[k]='\0';
}

void Transposition::tmakeArray(int col, int row)
{
	int i, j;

	for (i = 0; i < row; i++)
	{
		darr[i][col] = temp2[i];
	}
}

int Transposition::tfindMin()
{
	int i, j, min, index;

	min = temp[0];
	index = 0;
	for (j = 0; temp[j] != '\0'; j++)
	{
		if (temp[j] < min)
		{
			min = temp[j];
			index = j;
		}
	}

	temp[index] = 123;
	return (index);
}

int main(int argc, char** argv)    // main method 
{
	int opa, ope;
	char flag;

	cout << "\n Select Algorithm: \n";
	cout << "\n 1. Substitution :";
	cout << "\n 2. Transposition :";
	cin >> opa;
	fflush(stdin);
	if (opa == 1)
	{
		Substitution s;           			// creating object of Substitution class
		cout << "\n Substitution Cipher \n";
		s.sgetstring();

		cout << "\n What do you want to perform: \n";
		cout << "\n 1. Encryption :";
		cout << "\n 2. Decryption :";
		cin >> ope;

		if (ope == 1)
		{
			s.sencryption();
		}
		else
		{
			s.sdecryption();
		}
	}
	if (opa == 2)
	{
		Transposition t;						// creating object of Transposition class
		cout << "\n Transposition Cipher \n";
		t.tgetstring();

		cout << "\n What do you want to perform: \n";
		cout << "\n 1. Encryption :";
		cout << "\n 2. Decryption :";
		cin >> ope;

		if (ope == 1)
		{
			t.tencryption();
		}
		else
		{
			t.tdecryption();
		}
	}

	cout << "\n\n\n Done";
	//getch();
	cin >> flag;

	return (0);
}

SupaBeast (2)

For clarity I am using Visual Studio Community.

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