C++ iostreams provide a method to output (void *) pointers. The pointer is written to and read from a stream in hexadecimal notation.
How can I use decimal notation without resorting to a reinterpret_cast and ugly #ifdefs?
I tried this:
std::stringstream ss;
void *test = (void *)0x12345678;
// Output pointer as decimal number
ss << std::ios::dec << test; // Works!
// Read pointer from decimal number
void *x;
ss << dec; // Nope
ss.setf(std::ios::dec); // No change
ss >> dec >> x; // Neither
All the input variants do nothing. The pointer will not be assigned and keeps its "help I'm uninitialized" value of 0xcccccccc. The fail bit of the stream is set - probably because it tried to _still_ parse the number in hex and it was too large.
Professional C++ and .NET developer trying to break into indie game development.
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It might not answer your question, but why do you want to (a) write the pointer out in decimal, and (2) why on Mars would you want to read in a pointer?
Stephen M. Webb
Professional Free Software Developer
[s]I suspect the former program is actually calling a built in operator >> after some type converting, for example converting the two sides to booleans or something.[/s] (See Alvaro's response, I am wrong).
Calling `operator>>(std::cin, foo)' explicitly doesn't work if foo is an int either.
Reading a pointer from a stream is a valid operation, but there is no guarantee that the accepted format is decimal. In g++ the format seems to be hexadecimal. I can't bother to look it up in the standard, but my guess is that the only guarantee is that it will understand whatever format `<< foo' spits out.
Calling `operator>>(std::cin, foo)' explicitly doesn't work if foo is an int either.
[/quote]
Interesting, Needless to say, I don't explicitly call operators like that often. I was hoping an explicit call would allow me to "jump to declaration" in my IDE.
Reading a pointer from a stream is a valid operation...
[/quote]
Also interesting. Yet another entry in the C++ minefield to watch out for.
