EsEnigma

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
int main(int argc, char ** argv){
    /*
     * Read a file. for each character, offset by N for the first value,
     * for every other value, N+previous char value.
     * Example: enigma -n 3 ABC
     *    A+3=D=4
     *    B+4= G=6
     *    C+7=J=10
     * */

        if(argc !=3){
        printf("Usage: %s <integer offset> <inputfile.txt>\n", argv[0]);
    return -1;
        }
    int offset = atoi(argv[1]);
        //printf("Offset : %d\n",offset);
    FILE *file1=fopen(argv[2], "r"); //file to decode

        if(file1==NULL ){
        printf("Input Files ( %s ) Not Found\n", argv[2]);
        return 0;
        }
        int count =0;
            char c;  //file io char
        unsigned    int p; // previous character Index
    while(c!=EOF){
        c =tolower(fgetc(file1));
            if (count ==0){
            p=c+offset;
            //p=offset;
            printf("char: %c  Offset: %d value: %c \n",c,offset,c+offset);
            count ++;
            offset=p;
            }
            if (isalpha(c)>=97 || isalpha(c)<=122){
//get the previous index plus the index of the current value c
//offset = p + (c-'a'+1);
p=p-c-'a';
printf("P: %d \n",p);
offset = p + (c-'a'+1);

            //p=p+ (c-'a');
        //  offset = 1;
//printf("char: %c  Offset: %d value: %c \n",c,offset, c+offset);


                //deal with other non alphabet characters here
                printf(" ");

                }
}

//sleep(10);
//system("clear");
    return 0;
    }