hasdfj

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#define SIZE 4

//prototypes
void input(char[], int[]);
void encrypt(int[], const int [], int*, int*, int*);
void decrypt(int[], int*);

main()
{
    //2 variables to store number of times the code was entered successfully ot incorrectly
    int right;
    int wrong;
    //store chosen option
    char option;
    //store code that user entered
    char user_code[SIZE] = " ";
    //store converted code (from char to int)
    int int_code[SIZE] = {0};
    //access code that is constant
    const int access_code[SIZE] = {4, 5, 2, 3};
    //counter to check if code is already encrypted
    int already_encrypted;

    right = wrong = already_encrypted = 0;

    do
    {

        printf("\nPlease select an option\n");
        printf("1. Enter code\n");
        printf("2. Encrypt code and verify if correct\n");
        printf("3. Decrypt code\n");
        printf("4. Number of times code entered correctly and incorrectly\n");
        printf("5. Exit program\n\n");

        //read in user input
        scanf("%c", &option);

        //to determine which function to call
        switch(option)
        {
            //executes when option 1 is chosen
            case '1':
            {
                //will ignore numbers after the first if user enters more than one number (is the same for every case)
                flushall();

                //call function input()
                input(user_code, int_code);

                break;
            }//end case 1

            //executes when option 2 is chosen
            case '2':
            {
                flushall();

                //call function encrypt()
                encrypt(int_code, access_code, &right, &wrong, &already_encrypted);

                break;
            }//end case 2

            //executes when option 3 is chosen
            case '3':
            {
                flushall();

                //call funtion decrypt()
                decrypt(int_code, &already_encrypted);

                break;
            }//end case 3

            //executes when option 4 is chosen
            case '4':
            {
                flushall();
                clrscr();

                //prints number of times correct and number of times wrong
                printf("\nThe number of times the code was entered successfully is: \t%d \n", right);
                printf("The number of times the code was entered incorrectly is: \t%d \n", wrong);

                break;
            }//end case 4

            //executes when option 5 is chosen
            case '5':
            {
                flushall();
                clrscr();

                printf("\nProgram will now end.");

                break;
            }//end case 5


            //executes when user enters invalid option
            default:
            {
                flushall();

                printf("\nError: Invalid option chosen. \n");
                getchar();

                break;

            }//end default

        }//end switch


    }//end do
    while(option != '5');

    getchar();
}//end main()


/*Implement function input(). This function allows user to enter a 4-digit code that will
    be stored to be used in encryption process.
*/
void input(char user_code[SIZE], int int_code[SIZE])
{
    clrscr();

    int i;
    int error; //if there are values that aren't integers
    //int temp; //to store a value temporarily while converting from char to int

    error = 0;

    //prompt then read user input
    printf("\nPlease enter a %d-digit code.\n", SIZE);
    gets(user_code);

    //check if all values are numbers
    for(i = 0; i <SIZE ; i++)
    {
        switch(*(user_code + i))
        {
            //if values are numbers
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
            case '0':
            {
                break;
            }//end cases

            //if there is a value that is not an integer
            default:
            {
                error++;
                break;
            }//end default

        }//end switch

    }//end for

    //if there is an error
    if(error != 0)
    {
        printf("\n %d errors encountered.\n", error);
    }//end if
    else
    {

        //convert array of characters into array of integers
        for(i = 0; i < SIZE; i++)
        {
            *(int_code + i) = *(user_code + i) - '0';
        }//end for

    }//end else

}//end input()


/*Implement function encrypt(). This will encrypt the code that the user entered and it will
    then compare the encrypted code with the access code. If codes match, display message
    "CORRECT CODE". If codes don't match, display message "ERROR CODE".
*/
void encrypt(int int_code[SIZE], const int access_code[SIZE], int *right, int *wrong, int *already_encrypted)
{
    clrscr();

    //temporary variable to store values for swapping
    int temp;
    int i;
    int num;//for amount of matches out of 4 elements

    temp = num = 0;

    if(*already_encrypted == 0)
    {
        //swap elements
        for(i = 0; i < SIZE; i++)
        {
            //swap 1st and 3rd element
            if(i == 0)
            {
                //put 1st element in temp1
                temp = *(int_code + i);
                //put 3rd element in 1st position
                *(int_code + i) = *(int_code + (i+2));
                //put 1st element (stored in temp) in 3rd position
                *(int_code + (i+2)) = temp;
            }//end if

            //repeat previous if() but with 2nd and 4th elements
            if(i == 1)
            {
                temp = *(int_code + i);
                *(int_code + i) = *(int_code + (i+2));
                *(int_code + (i+2)) = temp;
            }//end if

        }//end for

        //add 1 to all elements
        for(i = 0; i < SIZE; i++)
        {
            *(int_code + i) = (*(int_code + i) + 1);

            //if value is 10, change it to 0
            if(*(int_code + i) == 10)
            {
                *(int_code + i) = 0;
            }//end if

        }//end for

        //check if codes match
        for(i = 0; i < SIZE; i++)
        {
            if(*(int_code + i) == *(access_code + i))
            {
                num++;
            }//end if

        }//end for

        //increments right by 1 if there are 4 matches
        if(num == SIZE)
        {
            *right = (*right + 1);
            printf("\nCORRECT CODE\n");
        }//end if
        else
        {
            *wrong = (*wrong + 1);
            printf("\nERROR CODE\n");
        }//end else

        *already_encrypted = 1;
    }//end if
    else
    {
        printf("\nThe code has already been encrypted.Cannot encrypt again.\n");
    }//end else

}//end encrypt()


/*Implement function decrypt(). This will allow the user to decrypt the code ONLY if the code has
    already been encrypted.
*/
void decrypt(int int_code[SIZE], int *already_encrypted)
{
    clrscr();

    int i;
    int temp = 0;

    if(*already_encrypted == 1)
    {
        //subtract 1 from all elements
        for(i = 0; i < SIZE; i++)
        {
            *(int_code + i) = (*(int_code + i) - 1);

            //if value is -1, change it to 9
            if(*(int_code + i) == -1)
            {
                *(int_code + 1) = 9;
            }//end if

        }//end for

        //swap elements
        for(i = 0; i < SIZE; i++)
        {
            //swap 1st and 3rd element
            if(i == 0)
            {
                //put 1st element in temp1
                temp = *(int_code + i);
                //put 3rd element in 1st position
                *(int_code + i) = *(int_code + (i+2));
                //put 1st element (stored in temp) in 3rd position
                *(int_code + (i+2)) = temp;
            }//end if

            //repeat previous if() but with 2nd and 4th elements
            if(i == 1)
            {
                temp = *(int_code + i);
                *(int_code + i) = *(int_code + (i+2));
                *(int_code + (i+2)) = temp;
            }//end if

        }//end for

        *already_encrypted = 0;

    }//end if
    else
    {
        printf("\nThe code has not been encrypted.\n");
    }//end else

}//end decrypt()