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

char get_key_number();
int key_ready();
char read_a_key();

void main()
{     int x;
	 for(x=1; x<=16; x++)
        { 
                cout<< "press  key  'a' to make sound" <<x<<  " \n";
                delay(1000);
		clrscr();
                if(read_a_key()=='a')
                {
                     sound(7000);
                     delay(300);
                     nosound();
                 } 
          }
}
char get_key_number () {	//return type of the function is char 
     char a; 
     _AH=0x00; 		//service number 0x00
     geninterrupt(0x16);  		//interrupt 0x16
     a=_AL; 		               //_AL is the key 
     return a;			//return the value
}

int key_ready() {//return 1 if a key is ready, 0 otherwise
long int x;
_AH=1;			//service number 0x01
geninterrupt(0x16);		//interrupt 0x16
x=_FLAGS&0x40;			//get flag register
if (x==0) {return 1;}	//if ZF==0 a key is ready
else return 0; 			//else no key
} 

char read_a_key() {		//return char if a key is ready
if (key_ready()) 
{return get_key_number();}
else return 0;
}