C programming command line clock continued (winclockv2): 365 programming project day thirty one

/* 
2010-01-31 john pfeiffer, MS windows clock

PROGRAM DESIGN
    MS window with X, quit button, and current system time displayed
    Hour:minute:second  (hh:mm:ss)

HIGH LEVEL FUNCTIONS

    update current time
    see if user clicked button
        quit if button clicked

    display current time on window


ORGANIC ITERATIVE BUILDS
    1. build a program to show current time (in c/dos) then exits immediately
        *TEST: should show correct system time 
        each time user presses enter show new current time (ctrl+c to exit)
        TEST: should show correct system time on each click

    2. build a windows "quit button app" (can reuse previous work)
        TEST: program should quit cleanly

    3. windows with current time (once) and quit button
        TEST: program should show correct system time and when button clicked quit

    4. windows with current time constantly updating and quit button
        (will the processor be overloaded while waiting?  need semaphores?)
*/



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

/*  
    stdio.h is for displaying output to command line
    time.h is for time()
    string.h is to help format any strings created
*/

/* returns a string with the current time */
void get_current_time( char current_time[] );

void display_time( char current_time[] );

void clear_current_time( char current_time[] );

int main(int argc, char* argv[])
{
        char c = 'n';
        char current_time[128];

    /* show that the string has garbage that is cleaned out */
        printf("\nDISPLAY current time variable (initial garbage)\n");
        display_time( current_time );

    /*
        Loop depending on the user to continue updating
    */
        do{

            printf("\nEMPTY current time variable.\n");
            clear_current_time( current_time );

            printf("\nDISPLAY current time variable:\n");
            display_time( current_time );

            printf("\nUPDATE current time variable.\n");
            get_current_time( current_time );

            /* DEBUGGING
            printf("%s\n", current_time);
            */

            printf("\nDISPLAY current time variable:\n");
            display_time( current_time );


            c = 'n';    /* ensure that the user must force a continuance */
            printf("\nPRESS y to update the current time variable again:\n");
            c = getchar();

        }while( c == 'y' );

        return 0;
}/* end main */

/* begin function definitions */

/* Get the current time from the system and update the time string */
void get_current_time( char current_time[128] )
{
        time_t tempTime;

        /* initialize the variable, otherwise only returns 1970 date */
        tempTime = time(NULL);

        /* DEBUGGING
        printf("%s\n", asctime(localtime(&tempTime)));
        */
        strcpy(current_time, asctime(localtime(&tempTime)));

        /* DEBUGGING
        printf("%s\n", current_time);
        */
}

/* output the current time string ... to the command line */
void display_time( char current_time[128] )
{
        printf("CURRENT TIME: %s\n",current_time);
}

void clear_current_time( char current_time[128] )
{
        memset( current_time, 0, sizeof(current_time));
}