Digital Analogue

Good find and thanks for translating. She's looking for a 22 year old rich guy with big feet. Hmm. --Andrew E

They are validating the username against several validation rules. One of them is 'eeUserName', which must match the following regex: ^(?=.*[0-9@_./-])(?=.*[a-zA-Z])([a-zA-Z0-9@_./-]){6,74}$ See if you can make heads or tails of it. I can't. --Bob

When I said "no warnings, no errors", I meant by default. If I compile -Wall (or -Wsign-compare) then yes, it does give a warning; but it gives that warning even if you are writing the correct version of the code! If you count up from zero and make the comparison "while (pennies < names.length())" you get precisely the same warning. So this is not at all helpful from a pedagogy perspective.

The standard is written that this kind of type conversion is normally silent, and the real problem here is that it's not even clear what names.length() returns (signed/unsigned), it's slightly difficult to find that out (and nearly impossible if you don't already have some idea of the potential problem), and at the point in a CS1 course where you might be doing this, the students may not even know the difference between signed and unsigned!

C++ has its place in the world. Intro CS courses are not that place.

--blahedo

"[...] the negative number is silently converted into a very large positive number. No warnings, no errors." What are you talking about? "warning: comparison between signed and unsigned integer expressions [-Wsign-compare]". But yes, I do see your point. --Johannes

C and C++ are rather low level, so they definitely need a little bit more experience, but bad code can be written in any language. I would rather choose Python, Ruby or Lua as an introductory language. --Studiosi

I agree this is painful, and like you I would not recommend C++ to students as a first programming language. However, as I work with C++ and run into things like these, I find looking at what the standard says to be somewhat helpful in cases like these. Often more so than library files. For example, for this particular issue, it looks like X::size_type itself is baked into the specification of C++, just like size_t. The fact that size_type for std::string resolves to size_t seems to be an implementation detail in itself. I could be wrong, but it looks like size_type for all types (std::string included) is defined as a part of allocator_traits, and they specify: "X::size_type: unsigned integer type a type that can represent the size of the largest object in the allocation model." Of course, having to look and half-understand the standard for someone new to C++ is unreasonable, and it is possible it doesn't match what the compiler does. But looking at standard library implementation files could be misleading as well (besides painful). --Oscar

Well, any programming language that I know of has its quirks, and it's possible to write bad code in all of them. The issue you highlight should yield a compiler warning however, so I'm not entirely sure that this qualifies as a case in point for C++ being a bad language for beginners. --GrandMaster789

Lua is the best introductory programming language. Fact. --Jon

So Don, I agree with you completely that C++ is a rather poor intro language (it can be a bear of a development language as well unless you can justify the performance gains). If you were king, which language(s) would you choose and why? --Chris Bortz

After 22 years teaching HS...I still could never quite get everything accomplished without many extra hours beyond the "40 hour work week"... --Jan