Compiling errors

Question

Im trying to compile but im getting these errors:

1>.\item.cpp(123) : warning C4800: 'int' : forcing value to bool 'true' or 'false' (performance warning)

1>.\commands.cpp(1372) : error C2057: expected constant expression
1>.\commands.cpp(1372) : error C2466: cannot allocate an array of constant size 0
1>.\commands.cpp(1372) : error C2133: 'buffer' : unknown size

Line 123 item.cpp

if((bool)random_range(0, 1))

Line 1372 commands.cpp

if(money < changeSexPrice)
{
char buffer[70 + changeSexPrice];
sprintf(buffer, "You do not have enough money. You need %d gold coins to change your sex.", changeSexPrice);
player->sendCancel(buffer);
return false;
}

any idea?

Answer 1

Your problem is char buffer[70 + changeSexPrice];. win32 compilers need a constant expression when doing stack allocation.

I'm not sure why you're adding changeSexPrice as you are only using the buffer to print an int. I bet if you pick a something like char buffer[1024] then you will have more than enough for your needs.

EDIT: Per the comments (which are very good).

If you use a fixed size buffer of len 1024, use snprintf. In Visual Studio's case, this is sprintf_s. Your code would change to:

sprintf_s(buffer, 1024, "You don't have enough money ...", yourValueHere);

Alternatively, Mark B presents an answer that removes the need for your own mem allocation as well.

Answer 2

if((bool)random_range(0, 1))

Better write something like:

if(random_range(0, 1) == 1)

This is clearer, and the warning will disappear.

Answer 3

Declaring variable length stack-based arrays is a gcc extension (and possibly others too). Use an ostringstream to do your formatting:

if(money < changeSexPrice)
{
    std::ostringstream os;
    os << "You do not have enough money. You need " << changeSexPrice << " gold coins to change your sex.";
    player->sendCancel(os.str().c_str());   // This assumes that sendCancel doesn't take ownership of its parameter.
    return false;
}