Prog#225: nl command

/*
nl command
Program#225
*/
#include<stdio.h>
main(int argc,char *argv[])
{
int i,j,p,h;
char a[200];
if(argc!=2)
{
printf("error: no.of arg");
return 0;
}
p=open(argv[1], 0);
if(p==-1)
{
printf("file open error");
return 0;
}
for(j=0,n=0;(i=read(p,&a[j],1))>0;j++)
{
if(a[j]=='\n')
{
n++;
a[j]='\0';
printf("%d %s", n,a);
j=-1;
}
}
close(p);
}