CODEWITHSUNDEEP
c++
Shamoon
Shamoon

Reputation: 43569

Is there a C++ equivalent to PHP's var_dump and die?

I know it's a simple question, but I'm looking to get my C++ groove on. I would imagine some sort of abort function could be used. But I don't think that'll return any text like die('hello'); would.

Upvotes: 2

Views: 9816

Answers (3)

Paolo
Paolo

Reputation: 15847

Assuming you need these equivalents for debugging purpose...

instead of die() you may invoke the debugger;

instead of var_export() you may inspect your variables content with the debugger.

Upvotes: -1

Konrad Rudolph
Konrad Rudolph

Reputation: 545875

I wouldn’t recommend calling std::abort, std::exit or anything like that.

It’s brute-force, and the semantics for proper cleanup are very complicated. You are essentially leaving (at least parts of) your program behind in a very messy state.

A much better way in C++ is to throw an exception which you then catch in main:

#include <stdexcept>

struct fatal_error : std::logic_error {
    fatal_error(char const* message) : std::logic_error(message) { }
};

int main() try {
    … the normal program flow starts here
} catch (fatal_error const& e) {
    std::cerr << e.what() << '\n';
    return EXIT_FAILURE;
}

Then, instead of die, you’d simply say throw fatal_error("Something went wrong.");.

Upvotes: 1

Mats Petersson
Mats Petersson

Reputation: 129454

There is no "print a message, then exit" in C or C++. You can quite easily write your own function for die (or panic, as I prefer to call it), something like:

void die(const std::string& msg)
{
    std::cerr << msg << std::endl;
    exit(1);
}

Or, if you want to avoid the problems with creating a string, which may fail under low memory conditons:

void die(const char *msg)
...

(the rest should be the same as above). The drawback here is that you can't trivially concatenate strings, e.g. die(std::string("Could not open file ") + filename); won't work with const char *.

A function that does var_dump is much harder, as there is no direct way to actually fetch the content of a variable of a an arbitrary type, or an array, in C++. You could perhaps do something like this:

template<typename T>
void var_dump(const T& var)
{
   std::cout << var << endl;
}

template<typename T, size_t N>
void var_dump(const T (&var)[N])
{
   for(i : var)
   {
      std::cout << i << endl;
   }
}

The latter is a bit like this PHP code: foreach($var as $i) echo $i . "\n";. And I may have the syntax slightly wrong, not sure.

Upvotes: 7

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