Write a C program to get and set System Date using Interrupt 21h.

# include <stdio.h>
# include <conio.h>
# include   <dos.h>

void GetSystemDate( );
void SetSystemDate( );

int main( )
{
    clrscr( );

    printf(" Current System Date is :: ");
    GetSystemDate( );

    printf("\n Setting new System Date....");
    SetSystemDate( );

    printf("\n New System Date is :: ");
    GetSystemDate( );

    getch( );
    return 0;
 }

 /* GetSystemDate( )  --*/
void GetSystemDate( )
 {
    union REGS InReg;
    union REGS OutReg;

    InReg.h.ah=0x2A;

    int86(0x21,&InReg,&OutReg);

    printf("%d-%d-%d",OutReg.h.dl,OutReg.h.dh,OutReg.x.cx);
 }

 /*SetSystemDate( ) --*/
void SetSystemDate( )
 {
    union REGS InReg;
    union REGS OutReg;

    InReg.h.ah=0x2B;
    InReg.h.dl=01;
    InReg.h.dh=01;
    InReg.x.cx=2004;

    int86(0x21,&InReg,&OutReg);
 }

Output:
Current System Date is :: 4-28-2013
Setting new System Date....
New System Date is :: 4-28-2013