ASCII to Binary revised version.

// Now handles two's compliment negative numbers, though I'm not convinced that it
// handles the codes correctly, certainly not UTF-8 encoding.
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
// Forward declaration of function:
int main();
// Global variables:
static char x[2]=" \0";
static char buffer='\0';
static char run=0;
static char i=0;
// This is used as a boolean so that the negative numbers are represented
// correctly in binary:
static char twoscompliment=0;
static int a=0;
// This array of type char will represent each binary digit that is 'on':
static char binary[8]="00000000";
int main()
{
    // Clears screen and sets welcome message (system (); might not work with Visual Studio 2010
    // but is fine with Code::Blocks):
    system("cls");
    printf("Welcome to this ascii and binary conversion programme.\n");
    printf("Please enter one character only and press the ENTER key.\n");
    printf("Entering two or more characters may crash this programme,\n");
    printf("or cause unusual results! (C) MMXII Donkeysoft.\n\n");
    // Tells the main element of the program to start, ie, everything in the
    // while() loop:
    run=1;
    while(run)
    {
        // Prompts for user input and gets the first two characters entered
        // by the user and stores in x at location zero and one:
        printf("\nEnter a character (press ENTER twice to exit)\nD:\\> ");
        x[0]=getchar(); x[1]=getchar();
        // Tests for condition to exit programme:
        if(x[0]=='\n' || x[0]=='\0')
        {
            // Says goodbye and switches off boolean to run:
            printf("\nGoodbye!");
            run=0;
            return 0;
        }
        // Outputs the character's ASCII value in decimal:
        printf("Character value in decimal: %d\n",x[0]);
        // Tests for negative numbers:
        if(x[0]<0)
        {
            twoscompliment=1;
            x[0]=x[0]+1;
        }
        else
            {
                twoscompliment=0;
            }
        // Sets each bit as appropriate:
        for(i=8;i>0;i=i-1)
            {
                // Stores the remainder of x[0] modulo 2 into a, so it will be
                // either 1 or zero, and then divides x[0] by 2:
                a=x[0]%2;
                x[0]=x[0]/2;
                // Tests to see if a is true or not:
                if(a && !twoscompliment)
                {
                    binary[i-1]='1';
                }
                else
                    if (!a && !twoscompliment)
                    {
                        binary[i-1]='0';
                    }
                else
                    if (a && twoscompliment)
                    {
                        binary[i-1]='0';
                    }
                else
                    if (!a && twoscompliment)
                    {
                        binary[i-1]='1';
                    }
            }
            // Now will output the contents of the character array called binary
            // as a string, containing ones and zeros for each bit set:
            printf("Character value in binary: %s\n",binary);
            if(twoscompliment)
            {
                printf("This is in two's compliment.\n");
            }
            printf("This reads as follows:\n");
            a=0;
            for(i=8; i>0; i=i-1)
            {
                printf("Bit %d is ",a);
                if(binary[i-1]=='1')
                {
                    printf("TRUE\n");
                }
                else
                    {
                        printf("FALSE\n");
                    }
                a=a+1;
            }
    }
}