Ошибка при cout в с

I ran across this error after just having installed vs 2010 and just trying to get a nearly identical program to work.

I’ve done vanilla C coding on unix-style boxes before, decided I’d play with this a bit myself.

The first program I tried was:

#include "stdafx.h"


int _tmain(int argc, _TCHAR* argv[])
{
    cout << "Hello World!";
    return 0;
}

The big thing to notice here… if you’ve EVER done any C coding,

int _tmain(int argc, _TCHAR* argv[])

Looks weird. it should be:

int main( int argc, char ** argv )

In my case I just changed the program to:

#include <iostream>
using namespace std;

int main()
{
     cout << "Hello world from  VS 2010!n";
     return 0;
}

And it worked fine.

Note: Use CTRL + F5 so that the console window sticks around so you can see the results.

I realize that there are several duplicates like this but none of them have worked for me so far.
I am trying to compile a C++ very simple program on Ubuntu using g++ but it is giving me scope errors.

#include <iostream>
using namespace std;

int main()
{
  cout << "Hello world";
}

This gives me this error:

sudo g++ -v test.c
test.c: In function ‘int main()’:
test.c:7:3: error: ‘cout’ was not declared in this scope

I also tried defining the scope as many other posts say, but that also didn’t work, but gave me a different error:

#include <iostream>

int main()
{
  std::cout << "Hello world";
}

Gives error:

test.c: In function ‘int main()’:
test.c:6:3: error: ‘cout’ is not a member of ‘std’

Most of the suggestions online suggest «using namespace std;», «#include » and «std::cout».
So I tried all 3 together, still no luck

#include <iostream>
using namespace std;

int main()
{
  std::cout << "Hello world";
}

gives error:

test.c: In function ‘int main()’:
test.c:7:3: error: ‘cout’ is not a member of ‘std’

I have gone through several forums online but none of them seem to work for me

This is a part of a bigger issue because of which one of my linux make doesn’t work.

Btw, I am using g++ and not gcc as a few posts messed up.

EDIT 1:

I changed the name to .cpp, and execute without sudo. Here is the verbose output:

pranoy@pranoyubuntu1210:~/Desktop/SIP/SIPp/sipp-3.3$ g++ -v test.cpp -o test
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.2-2ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686 --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 4.7.2 (Ubuntu/Linaro 4.7.2-2ubuntu1) 
COLLECT_GCC_OPTIONS='-v' '-o' 'test' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-linux-gnu/4.7/cc1plus -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE test.cpp -quiet -dumpbase test.cpp -mtune=generic -march=x86-64 -auxbase test -version -fstack-protector -o /tmp/cczzibvL.s
GNU C++ (Ubuntu/Linaro 4.7.2-2ubuntu1) version 4.7.2 (x86_64-linux-gnu)
    compiled by GNU C version 4.7.2, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/c++/4.7
 /usr/include/c++/4.7/x86_64-linux-gnu
 /usr/include/c++/4.7/backward
 /usr/lib/gcc/x86_64-linux-gnu/4.7/include
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
GNU C++ (Ubuntu/Linaro 4.7.2-2ubuntu1) version 4.7.2 (x86_64-linux-gnu)
    compiled by GNU C version 4.7.2, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 521527ea42f0901bf839bcaad0cb13e6
test.cpp: In function ‘int main()’:
test.cpp:5:3: error: ‘cout’ is not a member of ‘std’

#include <iostream>

int main()
{
    std::string name;

    std::cout << "Enter your name: ";

    std::cin >> name;

//С помощью одной команды cout можно вывести несколько значений
    std::cout << "Hello, " << name << "! n";
}

int a, b, c;

std::cout << "Enter a: ";
std::cin >> a;

std::cout << "Enter b: ";
std::cin >> b;

c = a + b;

std::cout << a << " + " << b << " = " << c;

std::string ageInput;
int age;

std::cout << "How old are you: ";
std::cin >> ageInput;

//В круглых скобках функции указывается значение, которое нужно конвертировать
age = stoi(ageInput);

std::cout << "You are " << age << " years old. n";

std::string ageInput;
int age = 0;

std::cout << "How old are you: ";
std::cin >> ageInput;

//Названия исключений можно посмотреть в сообщениях об ошибке
try
{
    age = stoi(ageInput);
}
catch(std::invalid_argument) 
{
    //Говорим, что можно вводить только числа
    std::cout << "Only numbers are allowed! n";
}
catch(std::out_of_range)
{
    //Говорим, что число слишком большое
    std::cout << "You can't be that old! n";
}
catch(...)
{
    //Если будет выброшено какое-то исключение, которое не обработано выше, то говорим, что возникла неизвестная ошибка
    std::cout << "Unknown error! n";
}

if(age > 0)
{
    std::cout << "You are " << age << " years old. n";
}
else
{
    std::cout << "Try again! n";
}

int action = 0;

//Выводим меню
std::cout << "===Calculator++==n1 - Additionn2 - Subtractionn3 - Divisionn4 - Multiplicationn5 - Quadratic equationnAction: ";

//Допускаем, что ввод будет верным
std::cin >> action;

switch(action)
{
    case 1:
   	 //Сложение
   	 break;

    case 2:
   	 //Вычитание
   	 break;

    case 3:
   	 //Деление
   	 break;

    case 4:
   	 //Умножение
   	 break;

    case 5:
   	 //Квадратные уравнения
	std::cout << 
   	 break;
}

double a, b, c, d, x1, x2;

std::cout << "ax^2 + bx + c = 0n";

std::cout << "a = ";
std::cin >> a;

std::cout << "b = ";
std::cin >> b;

std::cout << "c = ";
std::cin >> c;

d = (b * b) - 4 * a * c;

std::cout << "d = " << b << "^2 - 4 * " << a << " * " << c << "n";
std::cout << "d = " << d << "n";

if(d > 0)
{
    //Для работы функции sqrt() нужно подключить библиотеку cmath
    x1 = (-b + sqrt(d)) / (2 * a);
    x2 = (-b - sqrt(d)) / (2 * a);

    std::cout << "x1, x2 = (-" << b << " +- sqrt(" << d << ")) / (2 * " << a <<")n";
    std::cout << "x1 = " << x1 << "nx2 = " << x2 << "n";
}
else if(d == 0)
{
    x1 = -(b / (2 * a));
    std::cout << "x1, x2 = -(" << b << " / (2 * " << a << ")n";
    std::cout << "x1, x2 = " << x1 << "n";
}
else if(d < 0)
{
    std::cout << "No roots! n";
}

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