fileseek.c

#include <stdio.h>

int main(int argc, char* argv[])
{
    FILE        *fpt;
    char        byte;
    long int    where,move;

    if(argc != 2)
    {
        printf("Usage: fileseek filename\n");
        return(0);
    }

    fpt = fopen(argv[1], "r");

    if(fpt == NULL)
    {
        printf("Unable to open file %s for reading\n", argv[1]);
        return(0);
    }

    while(1)
    {
        where = ftell(fpt);

        fread(&byte,1,1,fpt);
        fseek(fpt,-1,SEEK_CUR);

        printf("Byte %d: %d (%c)\n", where, byte, byte);
        printf("Enter #bytes (+ or -) to move, or 0 to quit: ");

        scanf("%d", &move);

        printf("move: %d\n", move);

        if(move == 0)
            break;

        fseek(fpt,move,SEEK_CUR);
    }
    fclose(fpt);
}