linux c++ error: ‘ostream’ does not name a type

[niu shaoqing]

when I compile it :
hxjnsq@hxjnsq-VirtualBox:~$ g++ stat.cc
stat.cc:19:11: error: ‘ostream’ does not name a type
stat.cc:49:1: error: ‘ostream’ does not name a type
stat.cc: In function ‘int main(int, char**)’:
stat.cc:100:1: error: ‘cerr’ was not declared in this scope
stat.cc:104:1: error: ‘cout’ was not declared in this scope

I don't know why?

//stat.cc
#include<iostream>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<ostream>
class Stat : public stat
{
 private: 
   char *path;
   int fd;
public:
   Stat(){path=0;fd=-1;}
   ~Stat();
   Stat & examine(const char *pathname);
   Stat & examine(int fd);
   int operator==(Stat &o);
 
   friend ostream & operator<<(ostream &out , Stat &o);
};
 
Stat::~Stat()
{
if(path)
  delete path;
}
Stat & Stat::examine(const char *pathname)
{
   if(path)
      delete path;
   path=strdup(pathname);
   fd=-1;
   if(::stat(path,this)==-1)
      throw errno;
   return *this;
}
Stat & Stat::examine(int fd)
{
 if(path)
{
 delete path;
 path=0;
}
this->fd=fd;
if(::fstat(fd,this)==-1)
  throw errno;
return *this;
}
ostream & operator<<(ostream &out , Stat &o)
{
if(o.fd==-1&&!o.path)
{
out<<"No current infomation."
return out;
}
if(o.path)
  cout<<"stat("<<o.path<<"){\n";
else
  cout<<"fstat("<<o.fd<<"){\n";
cout<<"\tst_dev=\t"<<o.st_dev<<";\n"
<<"\tst_ino=\t"<<o.st_ino<<";\n";
 
cout.setf(ios::oct,ios::basefield);
cout<<"\tst_mode=\t"<<'0'<<o.st_mode<<";\n";
 
cout.setf(ios::dec,ios::basefield);
cout<<"\tst_nlink=\t"<<o.st_nlink<<";\n"
<<"\tst_uid=\t"<<o.st_uid<<";\n"
<<"\tst_gid=\t"<<o.st_gid<<";\n"
<<"\tst_rdev=\t"<<o.st_rdev<<";\n"
<<"\tst_atime=\t"<<o.st_atime<<";\n";
return out;
}
int Stat::operator==(Stat &o)
{
if(fd==-1&&!path)
throw EINVAL;
if(o.fd==-1 && !o.path)
throw EINVAL;
 
if(o.st_dev!=st_dev || o.st_ino!=st_ino)
return 0;
 
return 1;
}
 
int main(int argc,char **argv)
{
  int x;
  Stat t;
  Stat s;
  t.examine("./stat");
 
  for(x=1;x<argc;++x)
     {
try{
s.examine(argv[x]);
}catch(int e)
{
cerr<<strerror(e)<<":stat(2) of"
<<argv[x]<<"\n";
continue;
}
cout<<s<<"\n";
 
cout<<"'"<<argv[x]<<"' is"
<<(s==t?"same":"not the same")
<<"file as ./stat\n";
}
return 0;
}
 

[weaknessforcats]

You need to add using namespace std.