Question

I am facing a strange issue, working on my mac osx lion (under xcode4/clang, though it is reproducible with gcc4.2).

It seems, that I can not assign any value above 127 for a unsigned char variable. So, when I assign

v = (unsigned char) 156;

or, simply

std::cout << (unsigned char) 231 << std::endl;

my program does not produce any output.

When I run this code

std::cout << "Unsigned chars range up to " << UCHAR_MAX << std::endl;

I get the following output:

Unsigned chars range up to 255

However, when I run something like this, the program generates outputs up to some different arbitrary value (such as c = 114, c = 252, etc etc) each time.
for(unsigned char c = 0; c < CHAR_MAX; c++)
std::cout << “c = ” << 2*c << std::endl;

Changing the CHAR_MAX to UCHAR_MAX, the program ends without an output again 🙁

Thanks in advance

Answer 1

cout is converting the numeric value to a character from the character set (Well, it’s attempting to … when you don’t see anything it’s not a valid character for your charset, and technically it’s the terminal that’s deciding this).

Cast it to unsigned int instead.

Edit to add: ildjarn makes a very valid point in his comment to your question; if you ran this in the debugger you’d see that the value was indeed what you expected.