I hear Perl has weak typing with implicit type conversion. The only other language I know that has a powerful implicit type conversion system is C++. How does implicit type conversion work in Perl?
Conversion is done based on operator, and Perl has different operators for string and numeric operations. For example, == and eq are different operators, with the former doing numeric equivalence comparison, and the latter doing string equivalence comparison. The implicit conversion done to operands in each case is well defined and obvious.
Edit: Whoops, had operators reversed because I explained them after the fact. Fixed!
An operation may be evaluated in list or scalar context. For example, if you evaluate an array in list context, you get the members of the array, however, in scalar context, you get the number of elements in the array.
This idea is generalized to discuss different evaluation contexts for scalars. You might hear people discussing how a value behaves in boolean or string context. It's also common to talk about casting as "-ification", for example casting something to boolean context is "boolification".
By default, undefined values convert to empty string and 0. However, this can be made to generate a warning or even a fatal exception by setting the appropriate pragmas.
Generally in Modern Perl-style programming, strict and warnings are enabled, so implicit type conversion is not used as much these days. Warnings or errors are emitted.
I've found this greatly increases reliability.
An example is that I enabled those on the W3C checkers and a serious latent bug was discovered and fixed, even on code I wasn't familiar with.
