Unable to compile C++ program [closed]

Question

I was trying my hands to compile on Ubuntu. So I typed a this much small program :

#include <iostream>
using namespace std;
int main(){
int cases;
cin>>cases;
return 0;
}

And this thing giving lots of errors:

umair@ubuntu:~/cpp$ gcc -Wall -W -Werror 2.cpp -o 1
/tmp/ccU4nAIg.o: In function `main':
2.cpp:(.text+0x10): undefined reference to `std::cin'
2.cpp:(.text+0x15): undefined reference to `std::istream::operator>>(int&)'
/tmp/ccU4nAIg.o: In function `__static_initialization_and_destruction_0(int, int)':
2.cpp:(.text+0x4d): undefined reference to `std::ios_base::Init::Init()'
2.cpp:(.text+0x5c): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccU4nAIg.o:(.eh_frame+0x13): undefined reference to `__gxx_personality_v0'
collect2: error: ld returned 1 exit status

I can do this easily in "C" . But what's my mistake in "C++" ?

Answer 1

Use g++ instead of gcc to build your C++ program.

While gcc knows how to compile C++, by default it does not link against the C++ libraries that are required by your program.

From the manual:

Compiling C++ Programs

       C++ source files conventionally use one of the suffixes .C, .cc, .cpp, .CPP,
       .c++, .cp, or .cxx; C++ header files often use .hh or .H; and preprocessed C++
       files use the suffix .ii.  GCC recognizes files with these names and compiles
       them as C++ programs even if you call the compiler the same way as for
       compiling C programs (usually with the name gcc).

       However, the use of gcc does not add the C++ library.  g++ is a program that
       calls GCC and treats .c, .h and .i files as C++ source files instead of C
       source files unless -x is used, and automatically specifies linking against the
       C++ library.  This program is also useful when precompiling a C header file
       with a .h extension for use in C++ compilations.  On many systems, g++ is also
       installed with the name c++.

Answer 2

To compile C++, call g++ instead of gcc.