Programming

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char encrypt(char, char *);
int prompt(FILE **, FILE **, char *, char *, char *, char *); 

int main()
{
    FILE *inputFile, *outputFile;   // Self explantory
    char fileIn[256] = {'\0'}, fileOut[256] = {'\0'},
          password[30] = {'\0'}, password2[30] = {'\0'}; /* Input file name,  output file name and password and password2 */                                                                          
    int holding = 1, fcharin = 1, retStat;   /* Where we keep the byte from the file thats been
                                       encrypted and the byte read from the file */
                                     
    printf("XORencrypt by David James\nCreated: 29/05/08\n\n");

    retStat = prompt(&inputFile, &outputFile, fileIn, fileOut, password, password2);
    
         /*   Below is the encryption part.  Each byte from the file is read in to a (char) then XOR'd with element 0
            of the password array, then element 1 then element 2 etc until NULL is reached in the password array.  Then
            the now encrypted (char) byte is written to the output file.
         */ 

         while ( (fcharin = fgetc(inputFile)) != EOF ) {
            holding = encrypt(fcharin, password);
            fputc(holding, outputFile);
         }
         
    printf("\nEncryption/Decryption complete!\n");
               
    return 0;
}


/* The XOR encryption function */

char encrypt(char fcharin, char *password)
{
    int i = 0, holding = 0;
    
    for ( i = 0; password[i] != '\n'; i++ ) {
        holding = fcharin ^ password[i];
    }
    
    return holding; 
}

/* If the user gives no command line arguments */

int prompt(FILE **inputFile, FILE **outputFile, char *fileIn, char *fileOut, char *password, char *password2)
{
    printf("File to encrypt/decrypt?: ");
    scanf("%255s", fileIn);

         if ( (*inputFile = fopen(fileIn, "rb")) == NULL ) { 
            printf("Error opening file.\n");
            exit(1);
         }
    
         printf("Save the encrypted/decrypted file as?: ");
         scanf("%255s", fileOut);
      
        do {
            printf("Enter a password (less than 30 characters [no spaces]): ");
            scanf("%29s", password);
            printf("Again: ");
            scanf("%29s", password2);
        } while ( strcmp(password, password2) );
       
        if ( (*outputFile = fopen(fileOut, "wb")) == NULL ) { 
           printf("Error writing file %s or it could not be opened.\n", fileOut);
           exit(1);
        }

        return 0;
}

#include <stdio.h>
#include <stdlib.h>

/* prototype */
int prompt(FILE **);

int
main(int argc, char *argv)
{
    int fcharin;
    FILE *in;

    prompt(&in);

    while ((fcharin = fgetc(in)) != EOF )
      fprintf(stdout, "%d\n", fcharin);

    return 0;
}


int
prompt(FILE **inp)
{
   char fileIn[256];

   printf("File to encrypt/decrypt?: ");
   scanf("%255s", fileIn);

   if ((*inp = fopen(fileIn, "rb")) == NULL ) {          
       printf("Error opening input file.\n");
       exit(1);
   }
}