请帮我改一下，如何使数码管一开始时不显示任何东西

我的程序现在一开始时数码管显示乱码，请求教
#include<reg52.h>
#define uint unsigned int
#define uchar unsigned char
sbit dula=P2^6;
sbit wela=P2^7;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71,0};
uchar num,temp;
void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
uchar keyboardscan()
{
P3=0xfe;
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
delay(5);
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
temp=P3;
switch(temp)
{
case 0xee:num=1;
break;
case 0xde:num=2;
break;
case 0xbe:num=3;
break;
case 0x7e:num=4;
break;
}
}
}
P3=0xfd;
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
delay(5);
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
temp=P3;
switch(temp)
{
case 0xed:num=5;
break;
case 0xdd:num=6;
break;
case 0xbd:num=7;
break;
case 0x7d:num=8;
break;
}
}
}
P3=0xfb;
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
delay(5);
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
temp=P3;
switch(temp)
{
case 0xeb:num=9;
break;
case 0xdb:num=10;
break;
case 0xbb:num=11;
break;
case 0x7b:num=12;
break;
}
}
}
P3=0xf7;
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
delay(5);
temp=P3;
temp&=0xf0;
if(temp!=0xf0)
{
temp=P3;
switch(temp)
{
case 0xe7:num=13;
break;
case 0xd7:num=14;
break;
case 0xb7:num=15;
break;
case 0x77:num=16;
break;
}
}
}
return(0);
}
void display()
{
dula=1;
P0=table[num-1];
dula=0;
while(!0xf0);
delay(5);
while(!0xf0);
}
void main()
{
dula=1;
P0=0;
dula=0;
wela=1;
P0=0xc0;
wela=0;
while(1)
{
keyboardscan();
display();
}
}
[ 此贴被killer.chen在2010-03-29 23:01重新编辑 ]