[SOLVED] Learning C++ First Script won't compile

jmc1987 · 09-02-2010, 02:21 PM

I have decided to try out a little bit of c++ programing so I went out and bought me a book "Sams Teach your self C++ in 21 Days"

Now I am at the part of the book where you write the hello world script. when I run

Code:

gcc hello.cpp

I get this

Quote:

james@james-desktop:~/Desktop$ gcc hello.cpp
/tmp/ccYHXH5l.o: In function `main':
hello.cpp:(.text+0xa): undefined reference to `std::cout'
hello.cpp:(.text+0xf): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
/tmp/ccYHXH5l.o: In function `__static_initialization_and_destruction_0(int, int)':
hello.cpp:(.text+0x3d): undefined reference to `std::ios_base::Init::Init()'
hello.cpp:(.text+0x42): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccYHXH5l.o:(.eh_frame+0x12): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status

Far as I can see the correct is correct by the book.

hello.cpp file

Quote:

#include <iostream>
int main()
{
std::cout << "Hello World!\n";
return 0;
}

Here is my gcc -v output

Quote:

james@james-desktop:~/Desktop$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.3.3-5ubuntu4' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)

Thanks for the help. I am really lost right now.

14moose · 09-02-2010, 02:23 PM

Hi -

Don't use "gcc". Use "g++" instead. That should fix the problem

Here's a slight variation on your text book:

Code:

#include <iostream>

using namespace std;

int
main()
{
  cout << "Hello World!" << endl;
  return 0;
}

Quote:

g++ -o hello -Wall -pedantic hello.cpp

./hello
Hello World!

jmc1987 · 09-02-2010, 02:44 PM

Thanks so much. I guess gcc for C and g++ for c++?

thanks again

P.S.
I gave you a rep point

jmc1987 · 09-02-2010, 03:46 PM

Okay I am moving on and and ran into another issue. I tried to compile this code with

g++ exer.cpp

Quote:

#include <iostream>
int main()
{
int x = 5;
int y = 7;
std::cout << endl;
std::cout << x + y << " " << x * y;
std::cout << end;
return 0;
}

and I got the error

Quote:

james@james-desktop:~/Desktop$ g++ exer.cpp
exer.cpp: In function ‘int main()’:
exer.cpp:6: error: ‘endl’ was not declared in this scope
exer.cpp:10: error: ‘end’ was not declared in this scope

according to
http://gcc.gnu.org/gcc-4.3/porting_to.html to resove the error

Quote:

exer.cpp:6: error: ‘endl’ was not declared in this scope

add
using namespace std;

after
#include <iostream>

so now I can't figure out how to resolve these issues.

Quote:

exer.cpp: In function ‘int main()’:
exer.cpp:10: error: ‘end’ was not declared in this scope

Sorry for the trouble.

Thanks again

johnsfine · 09-02-2010, 04:15 PM

What do you think end is supposed to be in your code?

I assume you just need that to be endl

Did you make a typo in copying code from the book? Or did the author of the book make the typo?

Either way, the idea of using a book or tutorial is to try to understand the code you are copying, not just copy it. If you try to understand the code you are copying, you should have no trouble recognizing end was a typo for endl.

Samael · 09-02-2010, 04:46 PM

as 14moose put, if you type:

Code:

using namespace std;

under your include section it saves you from typing std:: before every cout and cin.

alan99 · 09-02-2010, 04:52 PM

You forgot to reference the namespace, it should be std::endl

Kenny_Strawn · 09-02-2010, 05:30 PM

Code:

#include <iostream>

using namespace std;

int main()
{
    int x = 5;
    int y = 7;
    cout << endl
         << x + y 
         << " " 
         << x * y;
    return 0;
}

^^
Fixed your code for you.

jmc1987 · 09-02-2010, 05:34 PM

No I am not just copying. The exercise is to determine what the code does then compiles it and see if I am right.

From the book word for word.

Quote:

1. Look at the following program and try to guess what it does without running it.

Quote:

#include <iostream>
int main()
{
int x = 5;
int y = 7;
std::cout << endl;
std::cout << x + y << " " << x * y;
std::cout << end;
return 0;
}

To get it compile using g++ I had to edit like this

Quote:

#include <iostream>
using namespace std;

int main()
{
int x = 5;
int y = 7;
cout << endl;
cout << x + y << " " << x * y;
cout << endl;
return 0;
}

So I suppose it a possible typo in the book?

Like I said the book "Sams Teach Yourself C++ in 21 Days" is publish by Sams which is a well known for Education References.

How ever I notice now I seem to be editing ever tutorial to get them to work.

And just to be sure gcc is a ansi compliant compiler right? I think the bookk may be written for a microsoft ansi compliant compiler. Not sure if that makes a big difference as I am a newbie here in the area.

Thanks again. It starting to work out. I'll let you guys know how things work out.

14moose · 09-02-2010, 05:46 PM

Hi -

1. Despite the best of intentions, many (most) books have typos.

But at least books have technical editors, and some kind of formal review process. My experience is that other resources (like net postings) are often worse.

2. Yes, you want "endl", not "end".
And yes, it's fully qualified name is "std::endl".

3. Yes, gcc is a C compiler, and g++ is a C++ compiler.

4. Yes, the snippet above builds and executes without error:

Code:

#include <iostream>

using namespace std;

int main()
{
  int x = 5;
  int y = 7;
  cout << endl;
  cout << x + y << " " << x * y;
  cout << endl;
  return 0;
}

Kenny_Strawn · 09-02-2010, 06:08 PM

Here's a build of that program that I was able to create:

Code:

#include <iostream>

using namespace std;

int main()
{
  int x;
  cout << "Enter a number: ";
  cin >> x;
  
  int y;
  cout << "Enter another number: ";
  cin >> y;
  
  cout << endl;
  cout << x + y << ", " << x * y;
  cout << endl;
  return 0;
}

Instead of declaring the variables and simply printing them, how about asking for them when the program runs?

Kenny_Strawn · 09-02-2010, 11:56 PM

Code:

echo $BUMP

andrei_b · 09-03-2010, 01:21 AM

or, as alan99 said:

Code:

std::cout << "Hi there!" << std::endl;

cout and endl both reside in std namespace.

ghostdog74 · 09-03-2010, 01:39 AM

Quote:

Originally Posted by jmc1987

I have decided to try out a little bit of c++ programing so I went out and bought me a book "Sams Teach your self C++ in 21 Days"

if this is not for homework/work and its just for learning how to program, i would suggest not using C++. Languages like Python/Perl etc doesn't need to be compiled, and you don't have to work with things like pointers, memory management etc. You will make good use of your time learning how to write algorithms and stuff, instead of figuring out how to compile properly, why your pointers doesn't work etc....

Perl:

Code:

printf "Enter a number: "
chomp($number=<>);
print "Number entered: $number\n";

Python:

Code:

number=raw_input("Enter a number:")
print "Number is ", str(number)

jmc1987 · 09-03-2010, 02:17 AM

I can do a little bit of perl like making calculations but I got a book on C++ so not I am going to learn it. But after I get the hang of C++ from what I understand I should practically be able to write alot of perl easier. So I have plans to jump into perl. The real reason of me wanting to learn some strong programming languages is so I can write some opensource programs.

Thanks for the help everyone.

Just a update on how things are going and for the people who have helped me and/or would like to know what I've done.

I am learning more about integers and stuff. So far I understands how functions work to. Also Learned how to figure out how much integers user in memory with

Quote:

#include <iostream>

int main()
{
using std::cout;

cout << "The size of an int is:\t\t"
<< sizeof(int) << " bytes.\n";
cout << "The size of a short int is:\t"
<< sizeof(short) << " bytes.\n";
cout << "The size of a short int is:\t"
<< sizeof(long) << " bytes.\n";
cout << "The size of char is:\t\t"
<< sizeof(char) << " bytes.\n";
cout << "The size of float is:\t\t"
<< sizeof(float) << " bytes.\n";
cout << "The size of a double is:\t"
<< sizeof(double) << " bytes.\n";
cout <<"The size of a bool is:\t"
<< sizeof(bool) << " bytes.\n";

return 0;
}

Hopefully in another week I might be able to start coding my own programs at the rate Im going.

Wish me Luck