Gas sensor code

#include<reg51.h>
sbit gas = P3^3;
sbit buzzer = P3^4;
void delay(unsigned int);
void main()
{
 while(1)
 {
  if(gas==1)
  {
    buzzer=0;
    delay(100);
  }
    buzzer=1;
  }
}
void delay(unsigned int n)
{
 unsigned char i;
 for(n;n>0;n--)
 {
  for(i=247;i>0;i--);
  for(i=247;i>0;i--);
 }
}