Write a program that will print “C” if compiled as

Question

Taken from http://www.ocf.berkeley.edu/~wwu/riddles/cs.shtml

It looks very compiler specific to me. Don't know where to look for?

Answer 1

You could try preprocessor directives, but that might not be what they are looking for.

Answer 2

Simple enough.

#include <stdio.h>
int main(int argc, char ** argv) {
#ifdef __cplusplus
printf("C++\n");
#else
printf("C\n");
#endif
return 0;
}

Or is there a requirement to do this without the official standard?

Answer 3

I'm guessing the intent is to write something that depends on differences between the languages themselves, not just predefined macros. Though it's technically not absolutely guaranteed to work, something like this is probably closer to what's desired:

int main() { 
    char *names[] = { "C", "C++"};

    printf("%s\n", names[sizeof(char)==sizeof('C')]);
    return 0;
}

Answer 4

Here's the program:

#include <stdio.h>

int main(int argc, char *argv[])
{
    printf("This is %s\n", sizeof 'a' == sizeof(char) ? "C++" : "C");
    return 0;
}

And here is some nice reading on C and C++ differences.

Answer 5

For what it's worth, here's another answer:

char x[sizeof(char *)+2], y[1];
printf("%.*s\n", sizeof(1?x:y)-sizeof(char *)+1, "C++");

Answer 6

Just look to see if the __STDC__ and __cplusplus compiler macros are defined.