help!!!!

i'm using c51.
i get an error"not in formal parameter list" and cannot
find a way to solve it,so i'm here to ask for ur help,please.
Here is my code:
#include <stdio.h>
#include <absacc.h>
#include <reg51.h>
#define uchar unsigned char
void serial() interrupt 4 using 1
uchar time[6],date[6];
uchar latitude[9],longitude[9];
uchar semisphere_f,semisphere_s;
uchar input_data="GPRMC";
uchar data_in;
int numbercomma;
bit flag;
if(SBUF==0x24)
{ if(SBUF==input_data) { flag=1; numbercomma=0; } else flag=0;
} if(flag==1) { if(SBUF==0x2c) { numbercomma++; } }

if(numbercomma==2)
{ data_in=SBUF;
} if (data_in=A) { swith(numbercomma) { case 1:time[6]=SBUF; case 3:latitude[9]=SBUF; case 4:semisphere_f=SBUF; case 5:longitude[9]=BUF; case 6:semisphere_s=SBUF; case 9:date[6]=SBUF; default:;break; } }

main()
{ TMOD=0x21; TH1=0xfa; TL1=0xfa; SCON=0x50; ES=1; EA=1;
} Thank you!