Boost C++ Libraries: Ticket #7661: lexical_cast throws exception when strings have more than one null terminators

Marshall Clow — Thu, 08 Nov 2012 21:43:28 GMT

I don't think this is a bug.

If you catch the exception, and display the what(), it says:bad lexical cast: source type value could not be interpreted as target.

I believe that what has happened is that it attempted to convert the two character sequence "0\0" to an integer, and that failed. This is the same thing that would happen if you appended (say), a 'Z' instead of a '\0'.

Why would you expect that to succeed?

pengxu7@… — Fri, 09 Nov 2012 14:32:23 GMT

If you print the std::string starting with 'm' following by multiple null terminators in std::cout, you will only see "0" not "0\0". I expect boost::lexical_cast to do the same for std::string, does it make sense?

Marshall Clow — Fri, 09 Nov 2012 14:54:11 GMT

A std::string is not a null terminated string.

The string that you have constructed is two characters long. The first character is a '0' (ASCII 48), and the second is a NUL (ASCII 0).

When you print that string, it prints _two_ characters - it's just that your console does not display the NULL.

If you build this program and run it, you would see "m" printed on your console.

#include <iostream>
int main( int argc, char *argv[] ) {
	std::string m = "0";
	m += '\0';
	std::cout << m;
}

But if you redirect the output to a file, and look at the file, you will see that the file is two characters long, with the second being the NULL.

pengxu7@… — Sat, 10 Nov 2012 13:43:56 GMT

ok, pls close it as it's an invalid bug.

status changed; resolution set

Marshall Clow — Sat, 10 Nov 2012 14:23:25 GMT

status new → closed
resolution → invalid