//I alos tried it...but u know i am beginner...this code is not logically write.i dont understand what to do knwo.....


#include <ATMEL/AT89X51.H>
void wait(void);
sbit column1=P1^4;
sbit column2=P1^5;
sbit column3=P1^6;
sbit row1=P1^0;
sbit row2=P1^1;
sbit row3=P1^2;
sbit row4=P1^3;
void rowscan(void);

void main(void)
{

while(1)
{

P1=0x0F;
if (row1==0||row2==0 ||row3==0 || row4==0)
{
rowscan();
}


}
}
void rowscan(void)
{
int a[4]={0,0,0,0},t=0,k,r,m=100;
static int sum=0;
if (column1==0 && row1==0)
{
a[t]=1;
}
if (column2==0 && row1==0)
{
a[t]=2;
}
if (column3==0 && row1==0)
{
a[t]=3;
}
if (column1==0 && row2==0)
{
a[t]=4;
}
if (column2==0 && row2==0)
{
a[t]=5;
}
if (column3==0 && row2==0)
{
a[t]=6;
}
if (column1==0 && row3==0)
{
a[t]=7;
}
if (column2==0 && row3==0)
{
a[t]=8;
}
if (column3==0 && row3==0)
{
a[t]=9;
}

if (column1==0 && row4==0)
{
a[t]=15;
}
if (column2==0 && row4==0)
{
a[t]=0;
}
if (column3==0 && row4==0)
{
a[t]=16;
}
t++;
for (k=0;k<3;k++)
{

if (a[k]==15)
{
r=0;
while (a[r]!=15 && r<4)
{
P2=0;
sum=sum+m*a[k];
m=m/10;
r++;
}


}
}

if (sum>0)
{
P2=sum;
}
wait();
}


void wait(void)
{
int f =0;
while (f<33000)
{
f++;

}

}