Question

I just got this book “Exploring C++” and I’m on my first lesson. I’ve been doing C# for a couple years as a hobby so i though why not give C++ a try.

In the book it says i need to setup my compiler to use standard C++. I am using visual studio 2010 so i did. http://msdn.microsoft.com/en-us/library/ms235629.aspx

but when i go to compile the code it all works fine except for one if statement.

i have triple checked just as instructed so it must be something with the tools.

specifically

if (not in) // this line here
{
    std::perror(argv[1]);
    return EXIT_FAILURE;

}

The full sample

#include <algorithm>
#include <fstream>
#include <iostream>
#include <iterator>
#include <ostream>
#include <string>
#include <vector>

void read(std::istream& in, std::vector<std::string>& text)
{
    std::string line;
    while (std::getline(in, line))
        text.push_back(line);
}

int main(int argc, char* argv[])
{
    std::vector<std::string> text;

    if (argc <2)
        read(std::cin, text);
    else 
    {
        std::ifstream in(argv[1]);
        if (not in)
        {
            std::perror(argv[1]);
            return EXIT_FAILURE;

        }
        read(in,text);
    }

    std::sort(text.begin(), text.end());

    std::copy(text.begin(), text.end(),
        std::ostream_iterator<std::string>(std::cout, "\n"));
}

I would really like to continue with this book so any help is greatly appreciated.

And I apologize if this is awfully noobish of me.

Answer 1

not is an “alternative token” for the boolean operator !.

Perhaps your compiler doesn’t support it.

Try this instead:

if (!in)

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Indeed, here’s exactly the same issue on another site.

VC compiler doesn’t by default recognize alternative tokens (they are exceedingly rare nowadays), but I believe this support may be turned on with a compiler switch.

In fact, Visual Studio requires that you #include <ciso646> to get support for alternative tokens, even though the C++ Standard states that this should have no effect¹. Naughty Visual Studio!

In any case, you might want to find a better, more modern textbook.

I recommend these resources.

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¹ [n3290: footnote 176]: In particular, including the standard header <iso646.h> or <ciso646> has no effect.