C++ programs not compiling

Question

I wrote a simple hello world program:

#include<bits/stdc++.h>
using namespace std;
   
int main(){
   cout<<"Hello";
}

But it is reporting an error:

In file included from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\bits\stl_algobase.h:64,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\bits\char_traits.h:39,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\ios:40,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\istream:38,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\sstream:38,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\complex:45,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\ccomplex:39,
                 from c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\mingw32\bits\stdc++.h:54,
                 from AAY.cpp:1:
c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\bits\stl_pair.h:214:11: error: expected unqualified-id before numeric constant
  214 |       _T1 7
      |           ^
c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\bits\stl_pair.h: In constructor 'constexpr std::pair<_T1, _T2>::pair()':
c:\mingw\lib\gcc\mingw32\9.2.0\include\c++\bits\stl_pair.h:245:9: error: class 'std::pair<_T1, _T2>' does not have any field named 'first'  
  245 |       : first(), second() { }

and so on.

Basically, it says that std::pair does not have a member named first although I haven't used any. Does anyone have a solution?

Probably header file corrupted. Uninstall and reinstall gcc. — user202729, Dec 13 '21 at 06:30
You can also use https://www.onlinegdb.com/ for small programs. — Mohit Maroliya B17CS036, Dec 13 '21 at 06:32
Also read this : https://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice — Pepijn Kramer, Dec 13 '21 at 06:36
The first two lines are (in)famous antipatterns; please don‘t use them. — Andrej Podzimek, Dec 13 '21 at 06:36
[Why should I not #include ?](https://stackoverflow.com/questions/31816095/why-should-i-not-include-bits-stdc-h) — Remy Lebeau, Dec 13 '21 at 06:49
It looks like someone or something has replaced a "first" in your header with a "7". Reinstall and make a fresh start - even if you successfully fix that prticular problem, there's no telling what else might be broken. — molbdnilo, Dec 13 '21 at 08:55

score 2 · Answer 1 · edited Dec 13 '21 at 06:34

2

You should not use

#include<bits/stdc++.h>

This is not a C++ compliant header file.

Please use #include <iostream> instead and it should be sufficient.

Of course you may have also a problem with your compiler installation.

edited Dec 13 '21 at 06:34

Afshin

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answered Dec 13 '21 at 06:32

Armin Montigny

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C++ programs not compiling

1 Answers1