ios has not been declared (C++)

[Nyap]

#include <iostream>
#include <fstream>
#include <cstdlib>

using std::ifstream;
using std::cout;

int main()
{
  ifstream input("input.txt", ios::nocreate);
  if (!input.is_open())
  {
  cout << "No input.txt found!\n";
  exit(0);
  }
  input.seekg(0, ios::end);
  int count_limit{input.tellg()};
}

||=== Build: Debug in Voweltest (compiler: GNU GCC Compiler) ===|
/media/nyap/acb384f6-b8a7-482b-b700-4070bd5c283b/learncpp/Voweltest/main.cpp||In function ‘int main()’:|
/media/nyap/acb384f6-b8a7-482b-b700-4070bd5c283b/learncpp/Voweltest/main.cpp|10|error: ‘ios’ has not been declared|
/media/nyap/acb384f6-b8a7-482b-b700-4070bd5c283b/learncpp/Voweltest/main.cpp|16|error: ‘ios’ has not been declared|
/media/nyap/acb384f6-b8a7-482b-b700-4070bd5c283b/learncpp/Voweltest/main.cpp|17|warning: unused variable ‘count_limit’ [-Wunused-variable]|
||=== Build failed: 2 error(s), 1 warning(s) (0 minute(s), 0 second(s)) ===|

wtf

 

[Tenshi_Okami]

#include <iostream>
#include <fstream>
#include <cstdlib>

using std::ifstream;
using std::cout;

int main()
{
  ifstream input("input.txt", ios::nocreate);
  if (!input.is_open())
  {
  cout << "No input.txt found!\n";
  exit(0);
  }
  input.seekg(0, ios::end);
  int count_limit{input.tellg()};
}

wtf

Ok so i barely know something from C++(Started to learn Yesterday) but have you declared what IOS is used for?

 

[Nyap]

what
Idk what you mean

 

[Tenshi_Okami]

Spoiler: One of the compile errors

error: ‘ios’ has not been declared

 

[Nyap]

ios is a class which ifstream is derived from (I think, I can't remember)

edit: yup pretty sure now

 

[Tenshi_Okami]

#include <iostream>
#include <fstream>
#include <cstdlib>

using std::ifstream;
using std::cout;

int main()
{
  int ios
  ifstream input("input.txt", ios::nocreate);
  if (!input.is_open())
  {
  cout << "No input.txt found!\n";
  exit(0);
  }
  input.seekg(0, ios::end);
  int count_limit{input.tellg()};
}

This seems to fix the IOS error, but then it gives me this

Spoiler: error

C:\Users\Angel\Documents\New folder\random\main.cpp|12|error: 'input' was not declared in this scope|

Like i said, i barely know C++ ;-;

 

[Nyap]

#include <iostream>
#include <fstream>
#include <cstdlib>

using std::ifstream;
using std::cout;

int main()
{
  int ios
  ifstream input("input.txt", ios::nocreate);
  if (!input.is_open())
  {
  cout << "No input.txt found!\n";
  exit(0);
  }
  input.seekg(0, ios::end);
  int count_limit{input.tellg()};
}

This seems to fix the IOS error, but then it gives me this

Spoiler: error

C:\Users\Angel\Documents\New folder\random\main.cpp|12|error: 'input' was not declared in this scope|

Like i said, i barely know C++ ;-;

that shouldn't work O_O
try compiling it on yours without the int ios and let me know if anything changes

 

[Tenshi_Okami]

Spoiler: lol

||=== Build: Debug in random (compiler: GNU GCC Compiler) ===|
C:\Users\Angel\Documents\New folder\random\main.cpp||In function 'int main()':|
C:\Users\Angel\Documents\New folder\random\main.cpp|10|error: 'ios' has not been declared|
C:\Users\Angel\Documents\New folder\random\main.cpp|16|error: 'ios' has not been declared|
C:\Users\Angel\Documents\New folder\random\main.cpp|17|warning: extended initializer lists only available with -std=c++11 or -std=gnu++11|
C:\Users\Angel\Documents\New folder\random\main.cpp|17|warning: unused variable 'count_limit' [-Wunused-variable]|
||=== Build failed: 2 error(s), 2 warning(s) (0 minute(s), 0 second(s)) ===|

Same thing as your error lol

 

[Nyap]

._. ill try updating gcc and see if that makes a difference

 

[Flyingsky]

I don't think nocreate is even neccesary, because you have an ifstream.
An ifstream doesn't create a file if it's not there, it just tries to open it and throws an error if there is no file.

 

[Tenshi_Okami]

wait no im dumd xD ignore this

 

[Nyap]

I don't think nocreate is even neccesary, because you have an ifstream.
An ifstream doesn't create a file if it's not there, it just tries to open it and throws an error if there is no file.

what sort of error

--------------------- MERGED ---------------------------

I found how to fix the ios error

#include <iostream>
#include <fstream>
#include <cstdlib>

using std::ifstream;
using std::cout;

int main()
{
  ifstream input("input.txt", std::ios::nocreate);
  if (!input.is_open())
  {
  cout << "No input.txt found!\n";
  exit(0);
  }
  input.seekg(0, std::ios::end);
  int count_limit{input.tellg()};
}

Now it only ask to fix the limit in int count_limit

idk why std:: fixed it but lol

I already tried that earlier - I get this

/media/nyap/acb384f6-b8a7-482b-b700-4070bd5c283b/learncpp/Voweltest/main.cpp|10|error: ‘nocreate’ is not a member of ‘std::ios {aka std::basic_ios<char>}’|

also, I just upgraded to g++6. No difference

 

[Flyingsky]

You can see that error with something like:

    ifstream input;
        input.open(file);

        if (input.fail())
        {
            perror(file.c_str());
            cout << endl;
        }

It will just say there is no file, if your program runs.

Oh and for the count limit, you may do something like:

	int length = input.tellg();

 

[Nyap]

You can see that error with something like:

    ifstream input;
        input.open(file);

        if (input.fail())
        {
            perror(file.c_str());
            cout << endl;
        }

It will just say there is no file, if your program runs.

ok, so it's not the program crashing kind of error, just failbit, right?
and whats perror?

 

[Flyingsky]

this is what perror does:

 

[Nyap]

ah ok

 

[Flyingsky]

I would write it like that:

#include <iostream>
#include <fstream>
#include <cstdlib>


using namespace std;

int main()
{
    ifstream input("input.txt");
    if (input.fail())
    {
        cout << "No input.txt found!\n";
        exit(1);
    }
    input.seekg(0, ios_base::end);
    int count_limit = input.tellg();
    cout << count_limit;
}

That should run