help im an idiot

please help me. this is my first day learning about programming and im stuck on lesson 2 of the online tuturial on this website. i havent done any courses or read any books yet. but when i go to do the example programme and compile it comes up with this error: [Warning] In function `int main()':
`cout' undeclared (first use this function)
(Each undeclared identifier is reported only
`cin' undeclared (first use this function)
even when i copy and paste the programme.

the programme is this:

Code:

---

include <iostream.h>                       
int main()                                //Most important part of the program!
{
  int age;                                //Need a variable...
  cout<<"Please input your age: ";        //Asks for age
  cin>>age;                                //The input is put in age
  if(age<100)                                //If the age is less than 100
  {
    cout<<"You are pretty young!";    //Just to show it works
  }
  else if(age==100)                //I use else just to show an example
  {
    cout<<"You are old";                //Just to show you it works...
  }
  else
  {
    cout<<"You are really old";        //Executed if no other statement is executed
  }
  return 0;
}

---

your assistance wil be muchly appreciated
thanks simon

what compiler are you using?
try this

Code:

---

#include <iostream>

using namespace std;

int main()//Most important part of the program!
{
  int age;//Need a variable...
  cout<<"Please input your age: ";//Asks for age
  cin>>age;//The input is put in age
  if(age<100)//If the age is less than 100
  {
    cout<<"You are pretty young!";    //Just to show it works
  }
  else if(age==100)//I use else just to show an example
  {
    cout<<"You are old";//Just to show you it works...
  }
  else
  {
    cout<<"You are really old";//Executed if no other statement is executed
  }
  return 0;
}

---

Only two things need to be changed:

Code:

---

#include <iostream> //Drop the .h

using namespace std; //Gets rid of the "undeclared" errors

int main()
{
  //code
  cin.get(); //You may want to use this to pause your program
  return 0;
}

---

So, just dropping the .h and adding using namespace std; should fix it, and cin.get(); will pause it if you want.

- SirCrono6

's about time the tutorials on the site got updated or a link added to one that conforms to currents standards

im using dev c++ 4.9.8.0 compiler. if i drop the .h from iostreasm and write in using namespace std then this messages appears
5 C:\My Documents\Untitled2.cpp parse error before `int'
8 C:\My Documents\Untitled2.cpp syntax error before `<<' token
9 C:\My Documents\Untitled2.cpp syntax error before `>>' token
In
instantiated from here

This code will work fine:

Code:

---

#include <iostream>                       

using namespace std;

int main()
{
  int age;
  cout << "Please input your age: ";
  cin >> age;
  if( age < 100 )
  {
    cout << "You are pretty young.";
  }
  else if( age == 100 )
  {
    cout << "You are old.";
  }
  else
  {
    cout << "You are really old.";
  }
  cin.ignore( 9999, '\n' );
  cin.get();
  return 0;
}

---

- SirCrono6

Code:

---

include <iostream.h>

---

should be

Code:

---

#include <iostream>

---

In response to WDT: the tutorials on the site are in the process of being updated.

Code:

---


#include <iostream>
#include <stblib.h>
using namespace std;
                       
int main()                                //Most important part of the program!
{
  int age;                                //Need a variable...
  cout<<"Please input your age: ";        //Asks for age
  cin>>age;                                //The input is put in age
  if(age<100)                                //If the age is less than 100
  {
    cout<<"You are pretty young!";    //Just to show it works
  }
  else if(age==100)                //I use else just to show an example
  {
    cout<<"You are old";                //Just to show you it works...
  }
  else
  {
    cout<<"You are really old";        //Executed if no other statement is executed
  }
  return 0;
}

---

make sure your creating a console application ;)

Why include stdlib.h there?? No reason to include that and if you need it I think the standard says its cstdlib

Also, the return 0; is extraneous.

Quote:

---

Originally posted by XSquared
Also, the return 0; is extraneous.

---

why extraneous??
he started with

Code:

---

int main()

---

for main function
it might extraneous if he wrote main function as

Code:

---

void main()

---

Quote:

---

Originally posted by M_Ghani
why extraneous??
he started with

Code:

---

int main()

---

for main function
it might extraneous if he wrote main function as

Code:

---

void main()

---

---

In C++, int main() implicitly returns 0.

Note: this does not apply to any other function.

Quote:

---

Originally posted by Dante Shamest
In C++, int main() implicity returns 0.

Note: this does not apply to any other function.

---

really????
that means that i can write int main() without writing return 0??????

Yes, technically, you can. The following code is valid:

Code:

---

int main() {}

---

Quote:

---

Originally posted by Dante Shamest
Yes, technically, you can. The following code is valid:

Code:

---

int main() {}

---

---

hey
i wrote a very simple program just to test that

Code:

---

#include<iostream>
using namespace std;
int main()
{
        int x;
        cout<<"enter number :\n";
        cin>>x;
        cout<<"number is :"<<x<<endl;
}

---

my compiler is Visual Studio 6

the program runs very well and it works but during compiling it gives errors which is

Quote:

---

E:\Program Files\Microsoft Visual Studio\MyProjects\34\h.cpp(9) : warning C4508: 'main' : function should return a value; 'void' return type assumed
Linking...

34.exe - 0 error(s), 1 warning(s)

---

>my compiler is Visual Studio 6
Visual C++ 6 doesn't conform very well to the C++ standard for various good reasons.

Depending on the compiler some will return a value of 0 in main by default and some won't..for instance VC++.

If your going to use stdlib.h you might as well go the route of system("pause"); but thenagain it isn't needed as most compilers agree with std::cin.get(); Mine however doesn't..for some odd reason..*goes to find out why..<_<*

Also you might not want to use the entire std namespace..

It would be more proper to use std::cout << " "; and std::cin >> x; if thats all your going to be using it for.

The reason your getting this error, is that cout and cin lye in a namespace called 'std'..compilers such as VC++ dont' care if you use std::cout << " "; or cout << " "; All std::cout << " "; does, is tell the compiler that you looking for cout in the namespace std.

see what u guys do? u guys make a small simple question huge.
heres a working program. just replace the middle stuff with whatever u need

Code:

---

#include <iostream>
using namespace std;

int main()
{

cout << "See how easy it is?!"; // Replace this with whatever code you want
return 0; // Works fine, stop complaining already!
}

---

>see what u guys do? u guys make a small simple question huge.
If everyone would just read our minds and do things properly there wouldn't be a problem. :D

Sry Prelude but I Must steal your >question thing, it's so cool.

>see what u guys do? u guys make a small simple question huge.

And not to mention, this doesn't solve his compiler errors.. If we give him more information, and then expound and divulge into it from there, it means that there is a greater possibility to fix his problem. More information = more chance that our answer(s) will fix his problem(s).

He's looking for a solution as to not only why he's getting an error, but how to fix it. He's not looking for a working program yet. He's looking to build his own working program, thats why he's on this board to learn.

But ya thats just my 2c.

Have we solve your problem?

thanks guys but im gonna have to agree with 00bootsy1. all i am is fricken confused. i dont know why the errors are happening i dont know how to fix them because i have tried everything. all i have done lately is copy and paste all your codes and not 1 has worked

seriously thinking about giving this up before i started. i even tried downloading borland compiler getting same $$$$. but i must admitt for some reason (i have no idea) 00bootsy1 code works

thanks simon

Borland C++ Builder 6.0

compiles, runs, and works fine.

Code:

---

//---------------------------------------------------------------------------

#include "vcl.h"
#include <iostream.h>
#pragma hdrstop

//---------------------------------------------------------------------------

#pragma argsused
int main(int argc, char* argv[])
{
int age;                                //Need a variable...
  cout<<"Please input your age: ";        //Asks for age
  cin>>age;                                //The input is put in age
  if(age<100)                                //If the age is less than 100
  {
    cout<<"You are pretty young!" << endl;    //Just to show it works
  }
  else if(age==100)                //I use else just to show an example
  {
    cout<<"You are old" << endl;                //Just to show you it works...
  }
  else
  {
    cout<<"You are really old" << endl;        //Executed if no other statement is executed
  }
  system("PAUSE");
  return 0;
}
//---------------------------------------------------------------------------

---

Are you sure you copied all of the code? Because I'm using Dev-C++ 4.9.8.0 too, and my code does work fine on it. So, my guess is that your doing something like not copying all of the code.

Code:

---

#include <iostream>                       

using namespace std;

int main()
{
  int age;
  cout << "Please input your age: ";
  cin >> age;
  if( age < 100 )
  {
    cout << "You are pretty young.";
  }
  else if( age == 100 )
  {
    cout << "You are old.";
  }
  else
  {
    cout << "You are really old.";
  }
  cin.get();
  cin.get();
  return 0;
}

---

- SirCrono6

Quote:

---

Originally posted by oobootsy1
see what u guys do? u guys make a small simple question huge.
heres a working program. just replace the middle stuff with whatever u need

Code:

---

#include <iostream>
using namespace std;

int main()
{

cout << "See how easy it is?!"; // Replace this with whatever code you want
return 0; // Works fine, stop complaining already!
}

---

---

The problem with your solution is why yours works and his doesn't. He's learned nothing.

okay. He's right, we should explain. Here goes.

#1

Code:

---

#include

---

whenever you include a header file, use a # in front of the 'include'

if you are the one making the header file, put quotes (" ") around the name, telling the compiuler to look in the main dir for this files. Else, put < > to tell the compiler to look in the main header folder.

example,
#include "myfile.h"
VS
#include <iostream.h>

#2

Code:

---

#include <iostream.h>

---

This is need for basic "cout" / "cin" functions

#3

Code:

---

using namespace std;

---

Don't recall what it does, but it its 100% needed!

#4

Code:

---

cout << "Hello world" << endl ;

---

this "endl" makes the next line of text spit out onto another line.

#5

Code:

---

int main(
int argc, char* argv[] )

---

this isn't needed, BUT, its good coding style.

#6

putting

Code:

---

return 0;

---

not really needed, but you should have it there. Main is jsut another function, and like all functions, it has to return somthing, in this case, '0'

Code:

---

void  main(int argc, char* argv[] }
{
cout << "hello world" << endl;
//no return value, because the funtion is void.
}

---

thats all i can think of off the top of my head, hope this helps some!

DW

you dont have to explain every thing .. this can be learned from books and tutorials but when there are errors with someone code we try to tell him what are his errors and explain to him why that is error and how to fix it ... not to explain the whole code line by line

>we try to tell him what are his errors and explain to him why that is error and how to fix it
That sounds like what we've been doing all along. You just have to wade through the dozen side conversations (that are all very interesting...sometimes) to find it.

>not to explain the whole code line by line
That's good because a line by line commentary is a real pain. I try to do it as little as possible because I have to explain not only what the code is doing, I also must describe what is wrong and why and how to do it right. The end result is usually a rather long post. I don't want to get carpal tunnel before I'm 30. :D

>I don't want to get carpal tunnel before I'm 30.
...she says after writing a rather long explanation of stuff dealing with binary trees. Are you saying that it's OK to get it in ~4 years?

>Visual C++ 6 doesn't conform very well to the C++ standard for various good reasons.
Just out of curiosity, what are those 'various good reasons'?

>Just out of curiosity, what are those 'various good reasons'?
Lack of a standard to conform to?

>Lack of a standard to conform to?
Pfft. That's not a valid excuse. No-one set any standards for me, and look at me now!

>and look at me now!
You don't really want me to comment on that, do you? ;)

>...she says after writing a rather long explanation of stuff dealing with binary trees. Are you saying that it's OK to get it in ~4 years?

I don't think that was the point she was trying to get across.

>Pfft. That's not a valid excuse. No-one set any standards for me, and look at me now!

Without standards, your code doesn't conform to everyone elses. Thus, your code cannot be easily joined by the numerous other programs developed from the standard. Hint:Your doing more work then you need to. There is a reason for standards, it keeps things clean and easy.

Quote:

---

Originally posted by Death_Wraith
#5

Code:

---

int main(int argc, char* argv[] )

---

this isn't needed, BUT, its good coding style.

---

What exactly is that and why is it good style? I always just delete it when the compiler adds it in heh.
:D

>What exactly is that
Arguments to main that allow you to take command line input from the program invocation.

>why is it good style?
If you don't use command line arguments then adding unnecessary clutter is bad style. You're also more likely to not get a clean compile if the compiler warns about unused variables.

If you don't understand what Prelude just said, this is a bit of a more detailed explenation.

Basically, main() is a function, and it can take various parameters like any other function. The parameters it can take are known as 'argc' of an int type, and '*argv[]', which is an array of char type(notice asteriks), this can take array elements of strings. 'argc' of an int type, is equal to the number of elements in '*argv[]'.

The first element in '*argv[]' is the filename of the source if I remember right. Then any other corresponding element in the array is whatever argument you pass to main() from the program invokator.

The program invokator, is the operating system alot of the time. So lets say you go into 'run' on a windows machine, and type in 'programname /?'.

'/?' is the argument that is passed into main() as *argv[1]. You can deal with arguments like any other function really. As an example:

Code:

---

int main(int argc, int *argv[])
{
  for (int x = 0; x < argc; x++)
  {
    if (argv[i] == "/?")
        //Handle argument here.
  return 0;
  }

---

Note that the program invokator is not limited to the operating system, and that 'argc' and '*argv[]' can be renamed to whatever you prefer.

Quote:

---

Originally posted by Prelude

That sounds like what we've been doing all along. You just have to wade through the dozen side conversations (that are all very interesting...sometimes) to find it.

---

Yeah I know that but I found Death_Wraith explaining line by line the code.. so i said that

Well I touched upon most of the arguments stated in this post.

#1 the include line
#2 the using namespace std;
#3 return 0;
#4 argc, int *argv[]
#5 etc...

<<Yeah I know that but I found Death_Wraith explaining line by line the code.. so i said that

I just pretty much summed up the whole post. Trying to make life easier! :D

ok i got the program working by copy and pasting sircrono6 code. but sircrono6 you asked me " am i coping the code properly" i assure you i have and the only reason your code worked is that you added 2 more lines to the bottom of the code. why does this fix the problem and why isnt it in tutorial then? how am i suppose to learn when its not even a full code. thanks for all your help but i think im gonna shoot myself in the foot. its probably a lot less painfull

Code:

---

cin.get();cin.get();

---

http://www.functionx.com/

Best tutorial ever.

BTW, what compiler are u using?

Quote:

---

Originally posted by vex
ok i got the program working by copy and pasting sircrono6 code. but sircrono6 you asked me " am i coping the code properly" i assure you i have and the only reason your code worked is that you added 2 more lines to the bottom of the code. why does this fix the problem and why isnt it in tutorial then? how am i suppose to learn when its not even a full code. thanks for all your help but i think im gonna shoot myself in the foot. its probably a lot less painfull

Code:

---

cin.get();cin.get();

---

---

Adding cin.get() to the end of main doesn't fix anything except for the fact that some development environments (e.g. MS VC++) keep the console window open after the program has terminated when run from the IDE and some (e.g. Dev-C++) don't. By adding cin.get() you pause the program until the user presses enter.

Adding cin.get() twice in a row is what people do when they don't realise why it doesn't work sometimes if you only add it once ;)

im using devc++ 4.9.8.0. thanks for the link to function X death wraith. im about to try it out now. hope its better than stupid one on this website.

p.s love the function x moto learn by practicing and practice by doing. ill get back to you on how i go. thanks for the help.

Quote:

---

Originally posted by vex
thanks for the link to function X death wraith. im about to try it out now. hope its better than stupid one on this website.

---

heck, nothing will replace a good C++ book :)

i know but im a cheap bastard. i have changed to c instead c++ and i aint having any problems. go figure aye. maybe if this goes alright ill buy a book

thanks all

p.s for all you tech heads out th there please keep your answers simple for the new kids. half the posts i didnt understand cause i wasnt that advanced yet. keep up the great forum guys.

bye for now

Quote:

---

Originally posted by vex
i know but im a cheap bastard. i have changed to c instead c++ and i aint having any problems. go figure aye. maybe if this goes alright ill buy a book

thanks all

p.s for all you tech heads out th there please keep your answers simple for the new kids. half the posts i didnt understand cause i wasnt that advanced yet. keep up the great forum guys.

bye for now

---

Sorry about that Vex, but good luck with C, I hope you do well in it :) If ya ever come back to here, I hope ya understand it better, been a good time, so cya later.