hai zulorain….
u just edit that code…
sbit red1=P0^0;
sbit red2=P0^1;
sbit red3=P0^2;
sbit red3=P0^3;
sbit green1=P0^4;
sbit green2=P0^5;
sbit green3=P0^6;
sbit green4=P0^7;
sbit buzzer=P1^3;
if(obj_distance<20){red1=red2=red3=red4=1;green1=green2=green3=green4=0;buzzer=1;}
else{red1=red2=red3=red4=0;green1=green2=green3=green4=1;buzzer=0;}
the conditional statements are placed in while condition.